CYTOCHROME-C(6) FROM THE GREEN-ALGA MONORAPHIDIUM-BRAUNII - CRYSTALLIZATION AND PRELIMINARY DIFFRACTION STUDIES - Frazao, C.; Dias, J. M.; Matias, P. M.; Romao, M. J.; Carrondo, M. A.; Hervas, M.; Navarro, J. A.; Delarosa, M.; Sheldrick, G. M. (Acta Crystallographica Section D-Biological Crystallography, 1995)
n/a
Times Cited: 6 Matias, Pedro/B-7180-2008; Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Matias, Pedro/0000-0001-6170-451X; Romao, Maria/0000-0002-3004-0543; 2 6

EXPRESSION OF DESULFOVIBRIO-GIGAS DESULFOREDOXIN IN ESCHERICHIA-COLI - PURIFICATION AND CHARACTERIZATION OF MIXED-METAL ISOFORMS - Czaja, C.; Litwiller, R.; Tomlinson, A. J.; Naylor, S.; Tavares, P; Legall, J.; Moura, J. J. G.; Moura, I.; Rusnak, F. (Journal Of Biological Chemistry, 1995)
The dsr gene from Desulfovibrio gigas encoding the nonheme iron protein desulforedoxin was cloned using the polymerase chain reaction, expressed in Escherichia coli, and purified to homogeneity. The physical and spectroscopic properties of the recombinant protein resemble those observed for the native protein isolated from D. gigas. These include an alpha(2) tertiary structure, the presence of bound iron, and absorbance maxima at 370 and 506 nm in the UV/visible spectrum due to ligand-to-iron charge transfer bands. Low temperature electron paramagnetic resonance studies confirm the presence of a high spin ferric ion with g values of 7.7, 5.7, 4.1, and 1.8. Interestingly, E. coli produced two forms of desulforedoxin containing iron. One form was identified as a dimer with the metal-binding sites of both subunits occupied by iron while the second form contained equivalent amounts of iron and zinc and represents a dimer with one subunit occupied by iron and the second with zinc.
n/a

Purification and Preliminary Characterization of Three C-Type Cytochromes from Pseudomonas Nautica Strain 617 - Saraiva, L. M.; Besson, S.; Moura, I.; Fauque, G. (Biochemical and Biophysical Research Communications, 1995)
n/a
n/a

REDOX AND SPIN-STATE CONTROL OF THE ACTIVITY OF A DIHEME CYTOCHROME-C PEROXIDASE - SPECTROSCOPIC STUDIES - Prazeres, S.; Moura, I.; Gilmour, R.; Pettigrew, G.; Ravi, N.; Huynh, B. H. (Nuclear Magnetic Resonance of Paramagnetic Macromolecules, 1995)
n/a
Times Cited: 3NATO Advanced Research Workshop on Nuclear Magnetic Resonance of Paramagnetic MacromoleculesJun 04-08, 1994Sintra, portugalNATO, Sci & Environm Affairs Div

Spectroscopic properties of the cytochrome CD1 from the marine denitrifier Pseudomonas nautica - Besson, S.; Carneiro, C.; Moura, J. J. G.; Moura, I.; Fauque, G. (Spectroscopy of Biological Molecules, 1995)
n/a
Times Cited: 06th European Conference on the Spectroscopy of Biological MoleculesSep 03-08, 1995Univ sci & technol lille, villeneuve dascq, franceInserm

TOTAL SYNTHESIS OF A SIMPLE METALLOPROTEIN - DESULFOREDOXIN - Tavares, P; Wunderlich, J. K.; Lloyd, S. G.; Legall, J.; Moura, J. J. G.; Moura, I. (Biochemical And Biophysical Research Communications, 1995)
Desulforedoxin is a protein purified from cellular extracts of Desulfovibrio gigas. It is a small (7.9 kDa) dimeric protein that contains a distorted rubredoxin like center (one single iron coordinated by four cysteinyl residues). Due to the simplicity of the polypeptide chain and of the iron center, an attempt was made to chemically produce this protein. A 36 amino acid polypeptide chain was synthesized based on the known sequence of native Desulforedoxin. The iron center was then reconstituted and the biochemical and spectroscopic characteristics of this synthetic protein were investigated. The final product has an equal sequence to the protein purified from D. gigas. The synthetic and natural Dr are very similar, in terms of redox potential and spectroscopic properties (UV-Visible, EPR, Mossbauer). (C) 1995 Academic Press, Inc.
n/a

Cloning, sequencing and overexpression of the Desulfovibrio gigas ferredoxin gene in E. coli - Chen, B.; Menon, N. K.; Dervertarnian, L.; Moura, J. J.; Przybyla, A. E. (FEBS Lett, 1994)
We have cloned the gene encoding Desulfovibrio gigas ferredoxin using a photodigoxigenin-labelled probe synthesized with the polymerase chain reaction. The DNA sequence of the gene predicts a polypeptide of 58 residues after removal of the initial formyl methionine (polypeptide M(r) = 6,276). The ferredoxin gene was expressed in aerobically grown E. coli behind the lac promoter of pUC18 resulting in a high level of ferredoxin expression which comprises about 10% of the total cell protein. EPR analysis of recombinant ferredoxin revealed the presence of a [3Fe-4S] cluster which is characteristic of native D. gigas ferredoxin II.
0014-5793 (Print)0014-5793 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Amino Acid Sequence; Base Sequence; Cloning, Molecular; Desulfovibrio/*genetics; DNA, Bacterial; Escherichia coli/*genetics; Ferredoxins/*genetics; Molecular Sequence Data; Recombinant Proteins/genetics; Spectrum Analysis

Quality and work organisation in Portuguese industry - Pereira, Zulema; António Moniz; Kovács, Ilona (University Library of Munich, Germany, 1994)
The present communication analyses the relationships between work organisation and quality systems. The analysis is based on results from a study funded by the "Specific Programme for the Development of Portuguese Industry" (PEDIP). The main issues which have been currently associated with work organisation and quality control in the Portuguese industry are characterized. Critical features related to the implementation of quality systems and new methods of work organisation for industrial development are also discussed. A few recommendations are given in order to promote appropriate methods of work organisation for quality improvement within Portuguese industry.
n/a
Keywords: industry; Portugal; quality; quality control; work organisation

{Quality and work organisation in Portuguese industry} - Pereira, Zulema; António Moniz; Kovács, Ilona (University Library of Munich, Germany, 1994)
The present communication analyses the relationships between work organisation and quality systems. The analysis is based on results from a study funded by the "Specific Programme for the Development of Portuguese Industry" (PEDIP). The main issues which have been currently associated with work organisation and quality control in the Portuguese industry are characterized. Critical features related to the implementation of quality systems and new methods of work organisation for industrial development are also discussed. A few recommendations are given in order to promote appropriate methods of work organisation for quality improvement within Portuguese industry.
n/a
Keywords: industry; Portugal; quality; quality control; work organisation

Hipóteses para uma hibridação de um sistema flex{\'ıvel de produção [Hipothesis for a flexible production system hybridation] - António Moniz (University Library of Munich, Germany, 1994)
In this paper one presents and discuss the hybridation concept using some aspect that integrate it, as the physical architecture of automated systems (hardware), the information system that integrates that architecture and the working places design. Analyzed are also the inter-dependences of those aspects, and we have as a reference the flexible production and assembly system existent at UNINOVA-CRI. The focus is made on possible problems that can occur with the use of possible development of those systems, namely: a) full automation with centralized human control, b) non-automated process of shop-floor work with a system “one man, one machine”, c) hybrid system of automated cells with “elastic” human jobs.
n/a
Keywords: automated system; automation; flexible production; hybrid system; information system

{Hipóteses para uma hibridação de um sistema flexível de produção [Hipothesis for a flexible production system hybridation]} - António Moniz (University Library of Munich, Germany, 1994)
In this paper one presents and discuss the hybridation concept using some aspect that integrate it, as the physical architecture of automated systems (hardware), the information system that integrates that architecture and the working places design. Analyzed are also the inter-dependences of those aspects, and we have as a reference the flexible production and assembly system existent at UNINOVA-CRI. The focus is made on possible problems that can occur with the use of possible development of those systems, namely: a) full automation with centralized human control, b) non-automated process of shop-floor work with a system “one man, one machine”, c) hybrid system of automated cells with “elastic” human jobs.
n/a
Keywords: automated system; automation; flexible production; hybrid system; information system

Evidence for a ternary complex formed between flavodoxin and cytochrome c3: 1H-NMR and molecular modeling studies - Palma, P. N.; Moura, I.; Legall, J.; Van Beeumen, J.; Wampler, J. E.; Moura, J. J. (Biochemistry, 1994)
Small electron-transfer proteins such as flavodoxin (16 kDa) and the tetraheme cytochrome c3 (13 kDa) have been used to mimic, in vitro, part of the complex electron-transfer chain operating between substrate electron donors and respiratory electron acceptors, in sulfate-reducing bacteria (Desulfovibrio species). The nature and properties of the complex formed between these proteins are revealed by 1H-NMR and molecular modeling approaches. Our previous study with the Desulfovibrio vulgaris proteins [Moura, I., Moura, J.J. G., Santos, M.H., & Xavier, A. V. (1980) Cienc. Biol. (Portugal) 5, 195-197; Stewart, D.E. LeGall, J., Moura, I., Moura, J. J. G., Peck, H.D. Jr., Xavier, A. V., Weiner, P. K., & Wampler, J.E. (1988) Biochemistry 27, 2444-2450] indicated that the complex between cytochrome c3 and flavodoxin could be monitored by changes in the NMR signals of the heme methyl groups of the cytochrome and that the electrostatic surface charge (Coulomb's law) on the two proteins favored interaction between one unique heme of the cytochrome with flavodoxin. If the interaction is indeed driven by the electrostatic complementarity between the acidic flavodoxin and a unique positive region of the cytochrome c3, other homologous proteins from these two families of proteins might be expected to interact similarly. In this study, three homologous Desulfovibrio cytochromes c3 were used, which show a remarkable variation in their individual isoelectric points (ranging from 5.5 to 9.5). On the basis of data obtained from protein-protein titrations followed at specific proton NMR signals (i.e., heme methyl resonances), a binding model for this complex has been developed with evaluation of stoichiometry and binding constants. This binding model involves one site on the cytochromes c3 and two sites on the flavodoxin, with formation of a ternary complex at saturation. In order to understand the potential chemical form of the binding model, a structural model for the hypothetical ternary complex, formed between one molecule of Desulfovibrio salexigens flavodoxin and two molecules of cytochrome c3, is proposed. These molecular models of the complexes were constructed on the basis of complementarity of Coulombic electrostatic surface potentials, using the available X-ray structures of the isolated proteins and, when required, model structures (D. salexigens flavodoxin and Desulfovibrio desulfuricans ATCC 27774 cytochrome c3) predicted by homology modeling.
0006-2960 (Print)0006-2960 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Amino Acid Sequence; Computer Graphics; Cytochrome c Group/*chemistry; Desulfovibrio/enzymology; Flavodoxin/*chemistry; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Sequence Data; Protein Conformation; Sequence Alignment

Thiol/disulfide formation associated with the redox activity of the [Fe3S4] cluster of Desulfovibrio gigas ferredoxin II. 1H NMR and Mossbauer spectroscopic study - Macedo, A. L.; Moura, I.; Surerus, K. K.; Papaefthymiou, V.; Liu, M. Y.; Legall, J.; Munck, E.; Moura, J. J. (J Biol Chem, 1994)
Desulfovibrio gigas ferredoxin II (FdII) is a small protein (alpha 4 subunit structure as isolated; M(r) approximately 6400 per subunit; 6 cysteine residues) containing one Fe3S4 cluster per alpha-subunit. The x-ray structure of FdII has revealed a disulfide bridge formed by Cys-18 and Cys-42 approximately 13 A away from the center of the cluster; moreover, the x-ray structure indicates that Cys-11 forms a disulfide bridge with a methanethiol. In the oxidized state, FdIIoxm the 1H NMR spectra, exhibit four low-field contact-shifted resonances at 29, 24, 18, and 15.5 ppm whereas the reduced state, FdIIR (S = 2), yields two features at +18.5 and -11 ppm. In the course of studying the redox behavior of FdII, we have discovered a stable intermediate, FdIIint, that yields 1H resonances at 24, 21.5, 21, and 14 ppm. This intermediate appears in the potential range where the cluster (E'0 approximately -130 mV) is reduced from the [Fe3S4]1+ to the [Fe3S4]0 state. FdIIint is observed during reductive titrations with dithionite or hydrogen/hydrogenase or after partial oxidation of FdIIR by 2,6-dichlorophenolindophenol or air. Our studies show that a total of three electrons per alpha-subunit are transferred to FdII. Our experiments demonstrate the absence of a methanethiol-Cys-11 linkage in our preparations, and we propose that two of the three electrons are used for the reduction of the disulfide bridge. Mossbauer (and EPR) studies show that the Fe3S4 cluster of FdIIint is at the same oxidation level as FdIIox, but indicate some changes in the exchange couplings among the three ferric sites. Our data suggest that the differences in the NMR and Mossbauer spectra of FdIIox and FdIIint result from conformational changes attending the breaking or formation of the disulfide bridge. The present study suggests that experiments be undertaken to explore an in vivo redox function for the disulfide bridge.
0021-9258 (Print)0021-9258 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Desulfovibrio/*metabolism; Disulfides/metabolism; Ferredoxins/*chemistry/*metabolism; Hydrogen; Kinetics; Magnetic Resonance Spectroscopy/methods; Oxidation-Reduction; Protein Conformation; Spectroscopy, Mossbauer/methods; Sulfhydryl Compounds/metabolism

Molecular cloning and sequence analysis of the gene of the molybdenum-containing aldehyde oxido-reductase of Desulfovibrio gigas. The deduced amino acid sequence shows similarity to xanthine dehydrogenase - Thoenes, U.; Flores, O. L.; Neves, A.; Devreese, B.; Van Beeumen, J. J.; Huber, R.; Romao, M. J.; Legall, J.; Moura, J. J.; Rodrigues-Pousada, C. (Eur J Biochem, 1994)
In this report, we describe the isolation of a 4020-bp genomic PstI fragment of Desulfovibrio gigas harboring the aldehyde oxido-reductase gene. The aldehyde oxido-reductase gene spans 2718 bp of genomic DNA and codes for a protein with 906 residues. The protein sequence shows an average 52% (+/- 1.5%) similarity to xanthine dehydrogenase from different organisms. The codon usage of the aldehyde oxidoreductase is almost identical to a calculated codon usage of the Desulfovibrio bacteria.
0014-2956 (Print)0014-2956 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov't
Keywords: *Genes, Bacterial; Aldehyde Oxidoreductases/*genetics; Amino Acid Sequence; Base Sequence; Cloning, Molecular; Desulfovibrio/*enzymology/genetics; DNA Primers/chemistry; Molecular Sequence Data; Molybdenum; Restriction Mapping; Sequence Alignment; Sequence Homology, Amino Acid; Xanthine Dehydrogenase/genetics

Primary sequence, oxidation-reduction potentials and tertiary-structure prediction of Desulfovibrio desulfuricans ATCC 27774 flavodoxin - Caldeira, J.; Palma, P. N.; Regalla, M.; Lampreia, J.; Calvete, J.; Schafer, W.; Legall, J.; Moura, I.; Moura, J. J. (Eur J Biochem, 1994)
Flavodoxin was isolated and purified from Desulfovibrio desulfuricans ATCC 27774, a sulfate-reducing organism that can also utilize nitrate as an alternative electron acceptor. Mid-point oxidation-reduction potentials of this flavodoxin were determined by ultraviolet/visible and EPR methods coupled to potentiometric measurements and their pH dependence studied in detail. The redox potential E2, for the couple oxidized/semiquinone forms at pH 6.7 and 25 degrees C is -40 mV, while the value for the semiquinone/hydroquinone forms (E1), at the same pH, -387 mV. E2 varies linearly with pH, while E1 is independent of pH at high values. However, at low pH (< 7.0), this value is less negative, compatible with a redox-linked protonation of the flavodoxin hydroquinone. A comparative study is presented for Desulfovibrio salexigens NCIB 8403 flavodoxin [Moura, I., Moura, J.J.G., Bruschi, M. & LeGall, J. (1980) Biochim. Biophys. Acta 591, 1-8]. The complete primary amino acid sequence was obtained by automated Edman degradation from peptides obtained by chemical and enzymic procedures. The amino acid sequence was confirmed by FAB/MS. Using the previously determined tridimensional structure of Desulfovibrio vulgaris flavodoxin as a model [similarity, 48.6%; Watenpaugh, K.D., Sieker, L.C., Jensen, L.H., LeGall, J. & Dubourdieu M. (1972) Proc. Natl Acad. Sci. USA 69, 3185-3188], the tridimensional structure of D. desulfuricans ATCC 27774 flavodoxin was predicted using AMBER force-field calculations.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Amino Acid Sequence; Base Sequence; Desulfovibrio/*chemistry; Electron Spin Resonance Spectroscopy; Flavodoxin/*chemistry; Hydrogen-Ion Concentration; Molecular Sequence Data; Oxidation-Reduction; Protein Structure, Tertiary; Sequence Homology, Amino Acid; Spectrophotometry, Ultraviolet; Spectrum Analysis

Mammalian ferrochelatase, a new addition to the metalloenzyme family - Ferreira, G. C.; Franco, R.; Lloyd, S. G.; Pereira, A. S.; Moura, I.; Moura, J. J.; Huynh, B. H. (J Biol Chem, 1994)
A [2Fe-2S] cluster has been detected in mammalian ferrochelatase, the terminal enzyme of the heme biosynthetic pathway. Natural ferrochelatase, purified from mouse livers, and recombinant ferrochelatase, purified from an overproducing strain of Escherichia coli, were investigated by electron paramagnetic resonance (EPR) and Mossbauer spectroscopy. In their reduced forms, both the natural and recombinant ferrochelatases exhibited an identical EPR signal with g values (g = 2.00, 1.93, and 1.90) and relaxation properties typical of [2Fe-2S]+ cluster. Mossbauer spectra of the recombinant ferrochelatase, purified from a strain of E. coli cells transformed with a plasmid encoding murine liver ferrochelatase and grown in 57Fe-enriched medium, demonstrated unambiguously that the cluster is a [2Fe-2S] cluster. No change in the cluster oxidation state was observed during catalysis. The putative protein binding site for the Fe-S cluster in mammalian ferrochelatases is absent from the sequences of the bacterial and yeast enzymes, suggesting a possible role of the [2Fe-2S] center in regulation of mammalian ferrochelatases.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Amino Acid Sequence; Animals; Electron Spin Resonance Spectroscopy; Escherichia coli; Ferrochelatase/*chemistry/genetics; Iron-Sulfur Proteins/chemistry; Liver/enzymology; Mice; Molecular Sequence Data; Recombinant Proteins/chemistry/genetics; Spectroscopy, Mossbauer

The kinetics of the oxidation of cytochrome c by Paracoccus cytochrome c peroxidase - Gilmour, R.; Goodhew, C. F.; Pettigrew, G. W.; Prazeres, S.; Moura, J. J.; Moura, I. (Biochem J, 1994)
In work that is complementary to our investigation of the spectroscopic features of the cytochrome c peroxidase from Paracoccus denitrificans [Gilmour, Goodhew, Pettigrew, Prazeres, Moura and Moura (1993) Biochem. J. 294, 745-752], we have studied the kinetics of oxidation of cytochrome c by this enzyme. The enzyme, as isolated, is in the fully oxidized form and is relatively inactive. Reduction of the high-potential haem at pH 6 with ascorbate results in partial activation of the enzyme. Full activation is achieved by addition of 1 mM CaCl2. Enzyme activation is associated with formation of a high-spin state at the oxidized low-potential haem. EGTA treatment of the oxidized enzyme prevents activation after reduction with ascorbate, while treatment with EGTA of the reduced, partially activated, form abolishes the activity. We conclude that the active enzyme is a mixed-valence form with the low-potential haem in a high-spin state that is stabilized by Ca2+. Dilution of the enzyme results in a progressive loss of activity, the extent of which depends on the degree of dilution. Most of the activity lost upon dilution can be recovered after reconcentration. The M(r) of the enzyme on molecular-exclusion chromatography is concentration-dependent, with a shift to lower values at lower concentrations. Values of M(r) obtained are intermediate between those of a monomer (39,565) and a dimer. We propose that the active form of the enzyme is a dimer which dissociates at high dilution to give inactive monomers. From the activity of the enzyme at different dilutions, a KD of 0.8 microM can be calculated for the monomerdimer equilibrium. The cytochrome c peroxidase oxidizes horse ferrocytochrome c with first-order kinetics, even at high ferrocytochrome c concentrations. The maximal catalytic-centre activity ('turnover number') under the assay conditions used is 62,000 min-1, with a half-saturating ferrocytochrome c concentration of 3.3 microM. The corresponding values for the Paracoccus cytochrome c-550 (presumed to be the physiological substrate) are 85,000 min-1 and 13 microM. However, in this case, the kinetics deviate from first-order progress curves at all ferrocytochrome c concentrations. Consideration of the periplasmic environment in Paracoccus denitrificans leads us to propose that the enzyme will be present as the fully active dimer supplied with saturating ferrocytochrome c-550.
0264-6021 (Print)0264-6021 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Animals; Ascorbic Acid/chemistry; Calcium/chemistry; Cytochrome c Group/*metabolism; Cytochrome-c Peroxidase/*metabolism; Heme/chemistry; Horses; Kinetics; Oxidation-Reduction; Paracoccus denitrificans/*enzymology

Ferromagnetic resonance of Fe(111) thin films and Fe(111)/Cu(111) multilayers - Rezende, S. M.; Moura, J. A.; de Aguiar, F. M.; Schreiner, W. H. (Phys Rev B Condens Matter, 1994)
n/a
0163-1829 (Print)0163-1829 (Linking)Journal article

The automobile sector and the organisation of the industrial space: the case of Setúbal Region (Portugal) - António Moniz (University Library of Munich, Germany, 1994)
This paper is based on a study about the Setúbal region, included in the internacional project “The Future of Industry in Europe” for the programme FAST-MONITOR of the European Community (1992-94). There were some information on the project VW/Ford for this region and those that are connected with research networks on industrial sectors (specially, on the automobile industry), and the network on the spatial and regional factors of regional development. Those studies allowed the scenario development on evolution trends of European industry and, specifically, on the automobile sector, and on the Setúbal region that was studied by the Portuguese team.
n/a
Keywords: automobile sector; greenfield site; Portugal; production models; regional development

Quality and work organization with advanced automation in Portugal - Pereira, Zulema; Kovács, Ilona; António Moniz (University Library of Munich, Germany, 1994)
In this paper it is analysed the relationships between work organisation and quality systems in firms that uses some forms of advanced automation. Are characterised the existing quality control structures in the Portuguese industry, and the main factors that hidden or fosters the development of sociotechnical methods of quality control organisation strategies. Are analysed some industrial cases that explains more clearly the critical issues of the implementation of quality systems and work organisation systems. A few recommendations are given about the possibilities for the development of new forms of work organisation and the quality systems associated to automated manufacturing systems.
n/a
Keywords: automation; organisation; Portugal; quality control systems; work organisation

Trends for the development of anthropocentric production systems in small less industrialised countries: The case of Portugal - Kovács, Ilona; António Moniz (University Library of Munich, Germany, 1994)
This paper analyses the problems and trends of the introduction of anthropocentric production systems (APS) in small less industrialized member states of the European Union, specifically the case of Portugal, based on the report for the FAST-Anthropocentric Technology Assessment Project (Monitor Programme) on “Prospects and conditions for APS in Europe by the 21st century”. Research teams from all countries of the European Community, as well as researchers from USA, Japan and Australia were participating in this project. The aim of this paper is to characterize APS and to present some special considerations related to the socioeconomic factors affecting the prospects and conditions for APS in Portugal. APS is defined as a system based on the utilization of skilled human resources and flexible technology adapted to the needs of flexible and participative organization. Among socioeconomic factors, some critical aspects for the development of APS will be focused, namely technological infrastructure, management strategies, perceived impact of introduction of automated systems on the division of labor and organizational structure, educational and vocational training and social actors strategies towards industrial automation. This analysis is based on a sample of industrial firms, built up for qualitative analysis, and on case studies analysis that can be reference examples for further development of APS, and not just for economic policy purposes alone. We have also analyzed the type of existing industrial relations, the union and employer strategies and some aspects of public policies towards the introduction of new technologies in the order to understand the extent to which there exist obstacles to and favorable conditions for the diffusion of anthropocentric systems. Finally some recommendations are presented to stress the trends for the implementation and development of anthropocentric production systems in Portugal.
n/a
Keywords: human resources; management strat; organization; Portugal; production systems; Technology Assessment

{Quality and work organization with advanced automation in Portugal} - Pereira, Zulema; Kovács, Ilona; António Moniz (University Library of Munich, Germany, 1994)
In this paper it is analysed the relationships between work organisation and quality systems in firms that uses some forms of advanced automation. Are characterised the existing quality control structures in the Portuguese industry, and the main factors that hidden or fosters the development of sociotechnical methods of quality control organisation strategies. Are analysed some industrial cases that explains more clearly the critical issues of the implementation of quality systems and work organisation systems. A few recommendations are given about the possibilities for the development of new forms of work organisation and the quality systems associated to automated manufacturing systems.
n/a
Keywords: automation; organisation; Portugal; quality control systems; work organisation

{The automobile sector and the organisation of the industrial space: the case of Setúbal Region (Portugal)} - António Moniz (University Library of Munich, Germany, 1994)
This paper is based on a study about the Setúbal region, included in the internacional project “The Future of Industry in Europe” for the programme FAST-MONITOR of the European Community (1992-94). There were some information on the project VW/Ford for this region and those that are connected with research networks on industrial sectors (specially, on the automobile industry), and the network on the spatial and regional factors of regional development. Those studies allowed the scenario development on evolution trends of European industry and, specifically, on the automobile sector, and on the Setúbal region that was studied by the Portuguese team.
n/a
Keywords: automobile sector; greenfield site; Portugal; production models; regional development

{Trends for the development of anthropocentric production systems in small less industrialised countries: The case of Portugal} - Kovács, Ilona; António Moniz (University Library of Munich, Germany, 1994)
This paper analyses the problems and trends of the introduction of anthropocentric production systems (APS) in small less industrialized member states of the European Union, specifically the case of Portugal, based on the report for the FAST-Anthropocentric Technology Assessment Project (Monitor Programme) on “Prospects and conditions for APS in Europe by the 21st century”. Research teams from all countries of the European Community, as well as researchers from USA, Japan and Australia were participating in this project. The aim of this paper is to characterize APS and to present some special considerations related to the socioeconomic factors affecting the prospects and conditions for APS in Portugal. APS is defined as a system based on the utilization of skilled human resources and flexible technology adapted to the needs of flexible and participative organization. Among socioeconomic factors, some critical aspects for the development of APS will be focused, namely technological infrastructure, management strategies, perceived impact of introduction of automated systems on the division of labor and organizational structure, educational and vocational training and social actors strategies towards industrial automation. This analysis is based on a sample of industrial firms, built up for qualitative analysis, and on case studies analysis that can be reference examples for further development of APS, and not just for economic policy purposes alone. We have also analyzed the type of existing industrial relations, the union and employer strategies and some aspects of public policies towards the introduction of new technologies in the order to understand the extent to which there exist obstacles to and favorable conditions for the diffusion of anthropocentric systems. Finally some recommendations are presented to stress the trends for the implementation and development of anthropocentric production systems in Portugal.
n/a
Keywords: human resources; management strat; organization; Portugal; production systems; Technology Assessment

Redox properties of Desulfovibrio gigas [Fe3S4] and [Fe4S4] ferredoxins and heterometal cubane-type clusters formed within the [Fe3S4] core. Square wave voltammetric studies - Moreno, C.; Macedo, A. L.; Moura, I.; Legall, J.; Moura, J. J. (J Inorg Biochem, 1994)
The same polypeptide chain (58 amino acids, 6 cysteines) is used to build up two ferredoxins in Desulfovibrio gigas a sulfate reducing organism. Ferredoxin II (FdII) contains a single [Fe3S4] core and ferredoxin I (FdI) mainly a [Fe4S4] core. The [Fe3S4] core can readily be interconverted into a [Fe4S4] complex (J.J.G. Moura, I. Moura, T.A. Kent, J.D. Lipscomb, B.H. Huynh, J. LeGall, A.V. Xavier, and E. Munck, J. Biol. Chem. 257, 6259 (1982)). This interconversion process suggested that the [Fe3S4] core could be used as a synthetic precursor for the formation of heterometal clusters. Co, Zn, Cd, and Ni derivatives were produced (I. Moura, J.J.G. Moura, E. Munck, V. Papaephthymiou, and J. LeGall, J. Am. Chem. Soc. 108, 349 (1986), K. Sureurs, E. Munck, I. Moura, J.J.G. Moura, and J. LeGall, J. Am. Chem. Soc. 109, 3805 (1986), and A.L. Macedo, I. Moura, J.J.G. Moura, K. Surerus, and E. Munck, unpublished results). The redox properties of a series of heterometal clusters (MFe3S4] are assessed using direct electrochemistry (square wave voltammetry--SWV) promoted by Mg(II) at a glassy carbon electrode (derivatives: Cd (-495 mV), Fe (-420 mV), Ni (-360 mV), and Co (-245 mV) vs normal hydrogen electrode (NHE)). In parallel, the electrochemical behavior (cyclic voltammetry--CV, differential pulse voltammetry--DPV and SWV) of FdI and FdII were investigated as well as the cluster interconversion process. In addition to the +1/0 (3Fe cluster) and +2/+1 (4Fe cluster) redox transitions, a very negative redox step, at -690 mV, was detected for the 3Fe core, reminiscent of a postulated further 2e- reduction step, as proposed for D. africanus ferredoxin III by F.A. Armstrong, S.J. George, R. Cammack, E.C. Hatchikian, and A.J. Thomson, Biochem. J. 264, 265 (1989). The electrochemical redox potential values are compared with those determined by independent methods (namely by electron paramagnetic resonance (EPR) and visible spectroscopy).
0162-0134 (Print)0162-0134 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Desulfovibrio/*chemistry; Electrochemistry; Electron Spin Resonance Spectroscopy; Ferredoxins/*chemistry; Ferrous Compounds/chemistry; Oxidation-Reduction; Spectrophotometry

Kinetic studies on the electron-transfer reaction between cytochrome c3 and flavodoxin from Desulfovibrio vulgaris strain Hildenborough - De Francesco, R.; Edmondson, D. E.; Moura, I.; Moura, J. J.; Legall, J. (Biochemistry, 1994)
The kinetic properties of the electron-transfer process between reduced Desulfovibrio vulgaris cytochrome c3 and D. vulgaris flavodoxin have been studied by anaerobic stopped-flow techniques. Anaerobic titrations of reduced cytochrome c3 with oxidized flavodoxin show a stoichiometry of 4 mol of flavodoxin required to oxidize the tetraheme cytochrome. Flavodoxin neutral semiquinone and oxidized cytochrome c3 are the only observable products of the reaction. At pH 7.5, the four-electron-transfer reaction is biphasic. Both the rapid and the slow phases exhibit limiting rates as the flavodoxin concentration is increased with respective rates of 73.4 and 18.5 s-1 and respective Kd values of 65.9 +/- 9.4 microM and 54.5 +/- 13 microM. A biphasic electron-transfer rate is observed when the ionic strength is increased to 100 mM KCl; however, the observed rate is no longer saturable, and relative second-order rate constants of 5.3 x 10(5) and 8.5 x 10(4) M-1 s-1 are calculated. The magnitude of the rapid phase of electron transfer diminishes with the level of heme reduction when varying reduced levels of the cytochrome are mixed with oxidized flavodoxin. No rapid phase is observed when 0.66e(-)-reduced cytochrome c3 reacts with an approximately 25-fold molar excess of flavodoxin. At pH 6.0, the electron-transfer reaction is monophasic with a limiting rate of 42 +/- 1.4 s-1 and a Kd value of approximately 8 microM. Increasing the ionic strength of the pH 6.0 solution to 100 microM KCl results in a biphasic reaction with relative second-order rate constants of 5.3 x 10(5) and 1.1 x 10(4) M-1 s-1. Azotobacter vinelandii flavodoxin reacts with reduced D. vulgaris cytochrome c3 in a slow, monophasic manner with limiting rate of electron transfer of 1.2 +/- 0.06 s-1 and a Kd value of 80.9 +/- 10.7 microM. These results are discussed in terms of two equilibrium conformational states for the cytochrome which are dependent on the pH of the medium and the level of heme reduction [Catarino et al. (1991) Eur. J. Biochem. 207, 1107-1113].
0006-2960 (Print)0006-2960 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Azotobacter vinelandii/metabolism; Cytochrome c Group/*metabolism; Desulfovibrio vulgaris/*metabolism; Electron Transport; Flavodoxin/*metabolism; Hydrogen-Ion Concentration; Kinetics; Models, Chemical; Oxidation-Reduction

Kinetic-Studies On The Electron-Transfer Reaction Between Cytochrome-C(3) And Flavodoxin From Desulfovibrio-vulgaris Strain Hildenborough - De Francesco, R.; Edmondson, D. E.; Moura, I.; Moura, J. J. G.; Legall, J. (Biochemistry, 1994)
The kinetic properties of the electron-transfer process between reduced Desulfovibrio vulgaris cytochrome c(3) and D. vulgaris flavodoxin have been studied by anaerobic stopped-flow techniques. Anaerobic titrations of reduced cytochrome c(3) with oxidized flavodoxin show a stoichiometry of 4 mol of flavodoxin required to oxidize the tetraheme cytochrome. Flavodoxin neutral semiquinone and oxidized cytochrome c(3) are the only observable products of the reaction. At pH 7.5, the four-electron-transfer reaction is biphasic. Both the rapid and the slow phases exhibit limiting rates as the flavodoxin concentration is increased with respective rates of 73.4 and 18.5 s(-1) and respective K-d values of 65.9 +/- 9.4 mu M and 54.5 +/- 13 CIM. A biphasic electron-transfer rate is observed when the ionic strength is increased to 100 mM KCl; however, the observed rate is no longer saturable, and relative second-order rate constants of 5.3 X 10(5) and 8.5 x 10(4) M(-1) s(-1) are calculated. The magnitude of the rapid phase of electron transfer diminishes with the level of heme reduction when varying reduced levels of the cytochrome are mixed with oxidized flavodoxin. No rapid phase is observed when 0.66e(-)-reduced cytochrome c(3) reacts with an similar to 25-fold molar excess of flavodoxin. At pH 6.0, the electron-transfer reaction is monophasic with a limiting rate of 42 +/- 1.4 s(-1) and a Kd value of similar to 8 mu M. Increasing the ionic strength of the pH 6.0 solution to 100 mu M KCl results in a biphasic reaction with relative second-order rate constants of 5.3 x 10(5) and 1.1 x 10(4) M(-1) s(-1) Azotobacter vinelandii flavodoxin reacts with reduced D. vulgaris cytochrome cs in a slow, monophasic manner with limiting rate of electron transfer of 1.2 +/- 0.06 s(-1) and a K-d value of 80.9 +/- 10.7 mu M. These results are discussed in terms of two equilibrium conformational states for the cytochrome which are dependent on the pH of the medium and the level of heme reduction [Catarino et al. (1991) Eur. J. Biochem. 207, 1107-1113].
Times Cited: 8

Spectroscopic properties of desulfoferrodoxin from Desulfovibrio desulfuricans (ATCC 27774) - Tavares, P; Ravi, N.; Moura, J. J.; Legall, J.; Huang, Y. H.; Crouse, B. R.; Johnson, M. K.; Huynh, B. H.; Moura, I. (J Biol Chem, 1994)
Desulfoferrodoxin, a non-heme iron protein, was purified previously from extracts of Desulfovibrio desulfuricans (ATCC 27774) (Moura, I., Tavares, P., Moura, J. J. G., Ravi, N., Huynh, B. H., Liu, M.-Y., and LeGall, J. (1990) J. Biol. Chem. 265, 21596-21602). The as-isolated protein displays a pink color (pink form) and contains two mononuclear iron sites in different oxidation states: a ferric site (center I) with a distorted tetrahedral sulfur coordination similar to that found in desulforedoxin from Desulfovibrio gigas and a ferrous site (center II) octahedrally coordinated with predominantly nitrogen/oxygen-containing ligands. A new form of desulfoferrodoxin which displays a gray color (gray form) has now been purified. Optical, electron paramagnetic resonance (EPR), and Mossbauer data of the gray desulfoferrodoxin indicate that both iron centers are in the high-spin ferric states. In addition to the EPR signals originating from center I at g = 7.7, 5.7, 4.1, and 1.8, the gray form of desulfoferrodoxin exhibits a signal at g = 4.3 and a shoulder at g = 9.6, indicating a high-spin ferric state with E/D approximately 1/3 for the oxidized center II. Redox titrations of the gray form of the protein monitored by optical spectroscopy indicate midpoint potentials of +4 +/- 10 and +240 +/- 10 mV for centers I and II, respectively. Mossbauer spectra of the gray form of the protein are consistent with the EPR finding that both centers are high-spin ferric and can be analyzed in terms of the EPR-determined spin Hamiltonian parameters. The Mossbauer parameters for both the ferric and ferrous forms of center II are indicative of a mononuclear high spin iron site with octahedral coordination and predominantly nitrogen/oxygen-containing ligands. Resonance Raman studies confirm the structural similarity of center I and the distorted tetrahedral FeS4 center in desulforedoxin and provide evidence for one or two cysteinyl-S ligands for center II. On the basis of the resonance Raman results, the 635 nm absorption band that is responsible for the gray color of the oxidized protein is assigned to a cysteinyl-S-->Fe(III) charge transfer transition localized on center II. The novel properties and possible function of center II are discussed in relation to those of mononuclear iron centers in other enzymes.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Desulfovibrio/*chemistry; Electron Spin Resonance Spectroscopy; Ferredoxins/*chemistry; Metalloproteins/*chemistry; Nonheme Iron Proteins; Oxidation-Reduction; Spectroscopy, Mossbauer; Spectrum Analysis, Raman

SUPRAMOLECULAR PHOTOCHEMISTRY AND PHOTOPHYSICS - 9-CYANOANTHRACENE IMPRISONED IN A HEMICARCERAND - A. J. Parola; Pina, F; Maestri, M; Armaroli, N.; Balzani, V. (New Journal of Chemistry, 1994)
The absorption and excited state properties of 9-cyanoanthracene are strongly modified upon inclusion into an octaimine hemicarcerand; the walls of the host do not transfer excitation to the guest and quench its fluorescent excited state.
ISI Document Delivery No.: NU948Times Cited: 11 Cited Reference Count: 18 Parola, aj pina, f maestri, m armaroli, n balzani, v Armaroli, Nicola/B-9094-2009; Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Gauthier-villars Paris

Dielectric relaxation in poly(n-alkyl methacrylate)s and their mixtures with p-nitroaniline - M. Dionísio; J. J. Moura Ramos; G. Williams (polymer, 1994)

Homotropic and heterotropic cooperativity in the tetrahaem cytochrome c3 from Desulfovibrio vulgaris - Turner, D.L.; Salgueiro, C.A.; Catarino, T.; Legall, J.; Xavier, A. V. (Biochimica et Biophysica Acta (BBA) - Bioenergetics, 1994)
The thermodynamic parameters which govern the homotropic (e−/e−) and heterotropic (e−/H+) cooperativity in the tetrahaem cytochrome c3 isolated from Desulfovibrio vulgaris (Hildenborough) were determined, using the paramagnetic shifts of haem methyl groups in the NMR spectra of intermediate oxidized states at different pH levels. A model is put forward to explain how the network of positive and negative cooperativities between the four haems and acid/base group(s) enables the protein to achieve a proton-assisted 2e− step.

ADENYLYLSULFATE REDUCTASES FROM SULFATE-REDUCING BACTERIA - Lampreia, J.; Pereira, A. S.; Moura, J. J. G. (ACADEMIC PRESS INC, 1994)
n/a
n/a

Aldehyde oxidoreductases and other molybdenum containing enzymes - Moura, J. J.; Barata, B. A. (Methods Enzymol, 1994)
n/a
0076-6879 (Print)0076-6879 (Linking)Comparative StudyJournal Article
Keywords: Amino Acid Sequence; Chromatography, DEAE-Cellulose/methods; Chromatography, Gel/methods; Chromatography, High Pressure Liquid/methods; Circular Dichroism; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Kinetics; Metalloproteins/*chemistry/*isolation & purification/metabolism; Molecular Sequence Data; Molecular Weight; Molybdenum/*analysis; Substrate Specificity; X-ray diffraction

CHARACTERIZATION OF 3 PROTEINS CONTAINING MULTIPLE IRON SITES - RUBRERYTHRIN, DESULFOFERRODOXIN, AND A PROTEIN CONTAINING A 6-IRON CLUSTER - Moura, I.; Tavares, P; Ravi, N. (1994)
n/a
n/a

Characterization of the Dihemic Cytochrome C549 from the Marine Denitrifying Bacterium Pseudomonas nautica 617 - Saraiva, L. M.; Besson, S.; Fauque, G.; Moura, I. (Biochemical and Biophysical Research Communications, 1994)
n/a
n/a

EXCITED-STATES OF ANTHOCYANINS - THE CHALCONE ISOMERS OF MALVIDIN 3,5-DIGLUCOSIDE - J. C. Lima; DANESH, P; FIGUEIREDO, P; PINA, FS; MACANITA, A (Photochemistry and Photobiology, 1994)
n/a
n/a

Ferredoxins - Moura, J. J.; Macedo, A. L.; Palma, P. N. (Methods Enzymol, 1994)
n/a
0076-6879 (Print)0076-6879 (Linking)Comparative StudyJournal Article
Keywords: *Protein Conformation; Amino Acid Sequence; Crystallography, X-Ray/methods; Cysteine; Desulfovibrio/*metabolism; Ferredoxins/*chemistry/*isolation & purification/metabolism; Iron/analysis; Macromolecular Substances; Metals/analysis; Models, Molecular; Molecular Sequence Data; Protein Structure, Secondary; Sequence Homology, Amino Acid; Species Specificity; Sulfur-Reducing Bacteria/*metabolism; Sulfur/analysis

FORMATION OF ANTHOCYANIN ION-PAIRS - A COPIGMENTATION EFFECT - FIGUEIREDO, P; Pina, F (Journal of the Chemical Society-Perkin Transactions 2, 1994)
n/a
Times Cited: 6 Figueiredo, Paulo/A-2078-2012; Figueiredo, Paulo/A-2429-2012; Figueiredo, Paulo/A-2425-2012; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Figueiredo, Paulo/0000-0002-8340-9316; Pina, Fernando/0000-0001-8529-6848; 6

INORGANIC MICROBIAL SULFUR METABOLISM (ACADEMIC PRESS INC, 1994)
n/a
n/a

MAMMALIAN FERROCHELATASE, A NEW ADDITION TO THE METALLOENZYME FAMILY - Ferreira, G. C.; Franco, R.; Lloyd, S. G.; Pereira, A. S.; Moura, I.; Moura, J. J. G.; Huynh, B. H. (Journal Of Biological Chemistry, 1994)
A [2Fe-2S] cluster has been detected in mammalian ferrochelatase, the terminal enzyme of the heme biosynthetic pathway. Natural ferrochelatase, purified from mouse livers, and recombinant ferrochelatase, purified from an overproducing strain of Escherichia coli, were investigated by electron paramagnetic resonance (EPR) and Mossbauer spectroscopy. In their reduced forms, both the natural and recombinant ferrochelatases exhibited an identical EPR signal with g values (g = 2.00, 1.93, and 1.90) and relaxation properties typical of [2Fe-2S](+) cluster. Mossbauer spectra of the recombinant ferrochelatase, purified from a strain of E. coli cells transformed with a plasmid encoding murine liver ferrochelatase and grown in Fe-57-enriched medium, demonstrated unambiguously that the cluster is a [2Fe-2S] cluster. No change in the cluster oxidation state was observed during catalysis, The putative protein binding site for the Fe-S cluster in mammalian ferrochelatases is absent from the sequences of the bacterial and yeast enzymes, suggesting a possible role of the [2Fe-2S] center in regulation of mammalian ferrochelatases.
n/a

MOLECULAR-CLONING AND SEQUENCE-ANALYSIS OF THE GENE OF THE MOLYBDENUM-CONTAINING ALDEHYDE OXIDOREDUCTASE OF DESULFOVIBRIO-GIGAS - THE DEDUCED AMINO-ACID-SEQUENCE SHOWS SIMILARITY TO XANTHINE DEHYDROGENASE - Thoenes, U.; Flores, O. L.; Neves, A.; Devreese, B.; Van Beeumen, J. J.; Huber, R.; Romao, M. J.; Legall, J.; Moura, J. J. G.; Rodriguespousada, C. (European Journal of Biochemistry, 1994)
n/a
Times Cited: 45 Devreese, bart/B-2011-2009; Romao, Maria/A-4115-2013; Moura, Jose/D-6426-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 46

PHOTOCHROMISM OF THE SYNTHETIC 4',7-DIHYDROXYFLAVYLIUM CHLORIDE - FIGUEIREDO, P; J. C. Lima; Santos, H.; WIGAND, MC; Brouillard, R; Macanita, AL; Pina, F (Journal of the American Chemical Society, 1994)
n/a
n/a

PHOTOPHYSICAL PROPERTIES AND PHOTODEGRADATION MECHANISM OF 2-(2'-FURANYL)-1H-BENZIMIDAZOLE (FUBERIDAZOLE) - Melo, MJ; Macanita, AL; Melo, E; Wamhoff, H.; Pina, F (Journal of Photochemistry and Photobiology a-Chemistry, 1994)
n/a
Times Cited: 3 Melo, Eurico/C-1297-2008; Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; Macanita, Antonio/H-9284-2012; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; Macanita, Antonio/0000-0003-0976-6654; 3

Physico-chemical and Spectroscopic Properties of the Monohemic Cytochrome C552 from Pseudomonas nautica 617 - Saraiva, Lígia M.; Fauque, Guy; Besson, Stéphane; Moura, Isabel (European Journal of Biochemistry, 1994)
A c-type monohemic ferricytochrome c552 (11 kDa) was isolated from the soluble extract of a marine denitrifier, Pseudomonas nautica strain 617, grown under anaerobic conditions with nitrate as final electron acceptor. The NH2-terminal sequence and the amino acid composition of the cytochrome were determined. The heme iron of the cytochrome c552 has histidine-methionine as axial ligands, and a pH-dependent mid-point redox potential, equal to 250 mV at pH 7.6. The presence of methionine was demonstrated by visible, EPR and NMR spectroscopies. The assignment of most of the hemic protons was performed applying two-dimensional NOE spectroscopy (NOESY), and the aromatic region was assigned through two-dimensional correlated spectroscopy (COSY) experiments. The EPR spectrum of the oxidised form of the cytochrome c552 is typical of a low-spin ferric heme.
n/a

Replacement of Methionine as the Axial Ligand of Achromobacter cycloclastes Cytochrome C554 at High pH Values Revealed by Absorption, EPR and MCD Spectroscopy - Saraiva, L. M.; Thomson, A. J.; Lebrun, N. E.; Liu, M. Y.; Payne, W. J.; Legall, J.; Moura, I. (Biochemical and Biophysical Research Communications, 1994)
n/a
n/a

SPECTROSCOPIC PROPERTIES OF DESULFOFERRODOXIN FROM DESULFOVIBRIO-DESULFURICANS (ATCC-27774) - Tavares, P; Ravi, N.; Moura, J. J. G.; Legall, J.; Huang, Y. H.; Crouse, B. R.; Johnson, M. K.; Huynh, B. H.; Moura, I. (Journal Of Biological Chemistry, 1994)
Desulfoferrodoxin, a non-heme iron protein, was purified previously from extracts of Desulfovibrio desulfuricans (ATCC 27774) (Moura, I., Tavares, P., Moura, J. J. G., Ravi, N., Huynh, B. H., Liu, M.-Y., and LeGall, J. (1990) J. Biol. Chem. 265, 21596-21602). The as-isolated protein displays a pink color (pink form) and contains two mononuclear iron sites in different oxidation states: a ferric site (center I) with a distorted tetrahedral sulfur coordination similar to that found in desulforedoxin from Desulfovibrio gigas and a ferrous site (center II) octahedrally coordinated with predominantly nitrogen/ oxygen-containing ligands. A new form of desulfoferrodoxin which displays a gray color (gray form) has now been purified. Optical, electron paramagnetic resonance (EPR), and Mossbauer data of the gray desulfoferrodoxin indicate that both iron centers are in the high-spin ferric states. In addition to the EPR signals originating from center I at g = 7.7, 5.7, 4.1, and 1.8, the gray form of desulfoferrodoxin exhibits a signal atg = 4.3 and a shoulder at g = 9.6, indicating a high-spin ferric state with E/D approximate to 1/3 for the oxidized center II. Redox titrations of the gray form of the protein monitored by optical spectroscopy indicate midpoint potentials of +4 +/- 10 and +240 +/- 10 mV for centers I and II, respectively. Mossbauer spectra of the gray form of the protein are consistent with the EPR finding that both centers are high-spin ferric and can be analyzed in terms of the EPR-determined spin Hamiltonian parameters. The Mossbauer parameters for both the ferric and ferrous forms of center II are indicative of a mononuclear high spin iron site with octahedral coordination and predominantly nitrogen/oxygen-containing ligands. Resonance Raman studies confirm the structural similarity of center I and the distorted tetrahedral FeS4 center in desulforedoxin and provide evidence for one or two cysteinyl-S ligands for center II. On the basis of the resonance Raman results, the 635 nm absorption band that is responsible for the gray color of the oxidized protein is assigned to a cysteinyl-S --> Fe(III) charge transfer transition localized on center II. The novel properties and possible function of center II are discussed in relation to those of mononuclear iron centers in other enzymes.
n/a

[15] Characterization of three proteins containing multiple iron sites: Rubrerythrin, desulfoferrodoxin, and a protein containing a six-iron cluster - Moura, Isabel; Tavares, Pedro; Ravi, Natarajan (Methods in Enzymology, 1994)
n/a
n/a

[16] Adenylylsulfate reductases from sulfate-reducing bacteria - Lampreia, Jorge; Pereira, Alice S.; Moura, José J. G. (Methods in Enzymology, 1994)
n/a
n/a

[20] Low-spin sulfite reductases - Moura, Isabel; Lino, Ana Rosa (Methods in Enzymology, 1994)
n/a
n/a

[21] Hexaheme nitrite reductase from Desulfovibrio desulfuricans (ATCC 27774) - Liu, Ming-Cheh; Costa, Cristina; Moura, Isabel (Methods in Enzymology, 1994)
n/a
n/a

Spectroscopic characterization of cytochrome c peroxidase from Paracoccus denitrificans - Gilmour, R.; Goodhew, C. F.; Pettigrew, G. W.; Prazeres, S.; Moura, I.; Moura, J. J. (Biochem J, 1993)
The cytochrome c peroxidase of Paracoccus denitrificans is similar to the well-studied enzyme from Pseudomonas aeruginosa. Like the Pseudomonas enzyme, the Paracoccus peroxidase contains two haem c groups, one high potential and one low potential. The high-potential haem acts as a source of the second electron for H2O2 reduction, and the low-potential haem acts as a peroxidatic centre. Reduction with ascorbate of the high-potential haem of the Paracoccus enzyme results in a switch of the low-potential haem to a high-spin state, as shown by visible and n.m.r. spectroscopy. This high-spin haem of the mixed-valence enzyme is accessible to ligands and binds CN- with a KD of 5 microM. The Paracoccus enzyme is significantly different from that from Pseudomonas in the time course of high-spin formation after reduction of the high-potential haem, and in the requirement for bivalent cations. Reduction with 1 mM ascorbate at pH 6 is complete within 2 min, and this is followed by a slow appearance of the high-spin state with a half-time of 10 min. Thus the process of reduction and spin state change can be easily separated in time and the intermediate form obtained. This separation is also evident in e.p.r. spectra, although the slow change involves an alteration in the low-spin ligation at this temperature rather than a change in spin state. The separation is even more striking at pH 7.5, where no high-spin form is obtained until 1 mM Ca2+ is added to the mixed-valence enzyme. The spin-state switch of the low-potential haem shifts the midpoint redox potential of the high-potential haem by 50 mV, a further indication of haem-haem interaction.
0264-6021 (Print)0264-6021 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Amino Acids/analysis; Cyanides/chemistry; Cytochrome-c Peroxidase/*chemistry; Electron Spin Resonance Spectroscopy; Heme/analysis; Magnetic Resonance Spectroscopy; Oxidation-Reduction; Paracoccus denitrificans/*enzymology; Spectrum Analysis

Characterization of D. desulfuricans (ATCC 27774) [NiFe] hydrogenase EPR and redox properties of the native and the dihydrogen reacted states - Franco, R.; Moura, I.; Legall, J.; Peck, H. D., Jr.; Huynh, B. H.; Moura, J. J. (Biochim Biophys Acta, 1993)
Redox intermediates of D. desulfuricans ATCC 27774 [NiFe] hydrogenase were generated under dihydrogen. Detailed redox titrations, coupled to EPR measurements, give access to the mid-point redox potentials of the iron-sulfur centers and of the Nickel-B signal that represents the ready form of the enzyme. The interaction between the dihydrogen molecule and the nickel centre was probed by the observation of an isotopic effect on the EPR signals detected in turnover conditions, by comparison of the H2O/H2 and D2O/D2-reacted samples.
0006-3002 (Print)0006-3002 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Binding Sites; Desulfovibrio/*enzymology/genetics; Electromagnetic Fields; Electron Spin Resonance Spectroscopy; Hydrogenase/*chemistry; Oxidation-Reduction; Temperature

Aldehyde oxidoreductase activity in Desulfovibrio gigas: in vitro reconstitution of an electron-transfer chain from aldehydes to the production of molecular hydrogen - Barata, B. A.; Legall, J.; Moura, J. J. (Biochemistry, 1993)
The molybdenum [iron-sulfur] protein, first isolated from Desulfovibrio gigas by Moura et al. [Moura, J. J. G., Xavier, A. V., Bruschi, M., Le Gall, J., Hall, D. O., & Cammack, R. (1976) Biochem. Biophys. Res. Commun. 72, 782-789], was later shown to mediate the electronic flow from salicylaldehyde to a suitable electron acceptor, 2,6-dichlorophenolindophenol (DCPIP) [Turner, N., Barata, B., Bray, R. C., Deistung, J., LeGall, J., & Moura, J. J. G. (1987) Biochem. J. 243, 755-761]. The DCPIP-dependent aldehyde oxidoreductase activity was studied in detail using a wide range of aldehydes and analogues. Steady-state kinetic analysis (KM and Vmax) was performed for acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde in excess DCPIP concentration, and a simple Michaelis-Menten model was shown to be applicable as a first kinetic approach. Xanthine, purine, allopurinol, and N1-methylnicotinamide (NMN) could not be utilized as enzyme substrates. DCPIP and ferricyanide were shown to be capable of cycling the electronic flow, whereas other cation and anion dyes [O2 and NAD(P)+] were not active in this process. The enzyme showed an optimal pH activity profile around 7.8. This molybdenum hydroxylase was shown to be part of an electron-transfer chain comprising four different soluble proteins from D. gigas, with a total of 11 discrete redox centers, which is capable of linking the oxidation of aldehydes to the reduction of protons.
0006-2960 (Print)0006-2960 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Aldehyde Oxidoreductases/isolation & purification/*metabolism; Desulfovibrio/*enzymology; Electron Transport; Enzyme Stability; Hydrogen/*metabolism; Kinetics; Substrate Specificity

Voltammetric studies of the catalytic electron-transfer process between the Desulfovibrio gigas hydrogenase and small proteins isolated from the same genus - Moreno, C.; Franco, R.; Moura, I.; Legall, J.; Moura, J. J. (Eur J Biochem, 1993)
The kinetics of electron transfer between the Desulfovibrio gigas hydrogenase and several electron-transfer proteins from Desulfovibrio species were investigated by cyclic voltammetry, square-wave voltammetry and chronoamperometry. The cytochrome c3 from Desulfovibrio vulgaris (Hildenborough), Desulfovibrio desulfuricans (Norway 4), Desulfovibrio desulfuricans (American Type Culture Collection 27774) and D. gigas (NCIB 9332) were used as redox carriers. They differ in their redox potentials and isoelectric point. Depending on the pH, all the reduced forms of these cytochromes were effective in electron exchange with hydrogenase. Other small electron-transfer proteins such as ferredoxin I, ferredoxin II and rubredoxin from D. gigas were tentatively used as redox carriers. Only ferredoxin II was effective in mediating electron exchange between hydrogenase and the working electrode. The second-order rate constants k for the reaction between reduced proteins and hydrogenase were calculated based on the theory of the simplest electrocatalytic mechanism [Moreno, C., Costa, C., Moura, I., Le Gall, J., Liu, M. Y., Payne, W. J., van Dijk, C. & Moura, J. J. G. (1993) Eur. J. Biochem. 212, 79-86] and the results obtained by cyclic voltammetry were compared with those obtained by chronoamperometry. Values for k of 10(5)-10(6) M-1 s-1 (cytochrome c3 as electron carrier) and 10(4) M-1 s-1 (ferredoxin II as the electron carrier) were determined. The rate-constant values are discussed in terms of the existence of an electrostatic interaction between the electrode surface and the redox carrier and between the redox carrier and a positively charged part of the enzyme.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: *Electron Transport; Catalysis; Cytochrome c Group/*metabolism; Desulfovibrio/*enzymology; Electrochemistry; Ferredoxins/*metabolism; Hydrogenase/*metabolism; Kinetics; Oxidation-Reduction; Rubredoxins/*metabolism

Organização do trabalho e controlo de qualidade numa estação de soldadura robotizada [Work organisation and quality control in a welding robotic cell] - António Moniz (University Library of Munich, Germany, 1993)
In this paper is analyzed the work organization and the forms of quality control in a robotic welding station in a company of office equipment and metal components manufacturing. The robotic cell is recent and works in two shifts. Quality and production rationalization implied in this firms the adoption of a strategy of organization of teamwork, and it is supported the collaborative tools to decrease the possibilities for errors and to improve means and methods of manufacturing. The analysis of quality control process needed the use of productivity indicators. In this way it was possible to understand the connections between the function quality and the new form of work organization adopted in this innovative experience in Portugal.
n/a
Keywords: innovation; quality control; welding robotics

{Organização do trabalho e controlo de qualidade numa estação de soldadura robotizada [Work organisation and quality control in a welding robotic cell]} - António Moniz (University Library of Munich, Germany, 1993)
In this paper is analyzed the work organization and the forms of quality control in a robotic welding station in a company of office equipment and metal components manufacturing. The robotic cell is recent and works in two shifts. Quality and production rationalization implied in this firms the adoption of a strategy of organization of teamwork, and it is supported the collaborative tools to decrease the possibilities for errors and to improve means and methods of manufacturing. The analysis of quality control process needed the use of productivity indicators. In this way it was possible to understand the connections between the function quality and the new form of work organization adopted in this innovative experience in Portugal.
n/a
Keywords: innovation; quality control; welding robotics

N-HYDROXY-N-PIVALOYLANILINES - A NEW AZIRIDINATING AGENT - Pereira, M. M.; SANTOS, PPO; REIS, LV; A. M. Lobo; Prabhakar, S. (JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1993)
n/a
n/a

REDUCTION OF NITROSOBENZENE BY 2-(ALPHA-HYDROXYETHYL)-3,4-DIMETHYLTHIAZOLIUM SALTS - Ferreira, LM; CHAVES, HT; A. M. Lobo; Prabhakar, S.; Rzepa, H. S. (JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1993)
n/a
n/a

Electrochemical studies of the hexaheme nitrite reductase from Desulfovibrio desulfuricans ATCC 27774 - Moreno, C.; Costa, C.; Moura, I.; Legall, J.; Liu, M. Y.; Payne, W. J.; Van Dijk, C.; Moura, J. J. (Eur J Biochem, 1993)
The electron-transfer kinetics between three different mediators and the hexahemic enzyme nitrite reductase isolated from Desulfovibrio desulfuricans (ATCC 27774) were investigated by cyclic voltammetry and by chronoamperometry. The mediators, methyl viologen, Desulfovibrio vulgaris (Hildenborough) cytochrome c3 and D. desulfuricans (ATCC 27774) cytochrome c3 differ in structure, redox potential and charge. The reduced form of each mediator exchanged electrons with nitrite reductase. Second-order rate constants, k, were calculated on the basis of the theory for a simple catalytic mechanism and the results, obtained by cyclic voltammetry, were compared with those obtained by chronoamperometry. Values for k are in the range 10(6)-10(8) M-1 s-1 and increase in the direction D. desulfuricans cytochrome c3-->D. vulgaris cytochrome c3-->methyl viologen. An explanation is advanced on the basis of electrostatic interactions and relative orientation between the partners involved. Chronoamperometry (computer controlled) offers advantages over cyclic voltammetry in the determination of homogeneous rate constants (faster, more accurate and better reproducibility). Direct, unmediated electrochemical responses of the hexaheme nitrite reductase were also reported.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Cytochrome c Group/metabolism; Desulfovibrio/*enzymology; Electrochemistry; Electron Transport; Kinetics; Nitrite Reductases/*chemistry/metabolism; Paraquat/metabolism

Subunit composition, crystallization and preliminary crystallographic studies of the Desulfovibrio gigas aldehyde oxidoreductase containing molybdenum and [2Fe-2S] centers - Romao, M. J.; Barata, B. A.; Archer, M.; Lobeck, K.; Moura, I.; Carrondo, M. A.; Legall, J.; Lottspeich, F.; Huber, R.; Moura, J. J. (Eur J Biochem, 1993)
The Desulfovibrio gigas aldehyde oxidoreductase contains molybdenum bound to a pterin cofactor and [2Fe-2S] centers. The enzyme was characterized by SDS/PAGE, gel-filtration and analytical ultracentrifugation experiments. It was crystallized at 4 degrees C, pH 7.2, using isopropanol and MgCl2 as precipitants. The crystals diffract beyond 0.3-nm (3.0-A) resolution and belong to space group P6(1)22 or its enantiomorph, with cell dimensions a = b = 14.45 nm and c = 16.32 nm. There is one subunit/asymmetric unit which gives a packing density of 2.5 x 10(-3) nm3/Da (2.5 A3/Da), consistent with the experimental crystal density, rho = 1.14 g/cm3. One dimer (approximately 2 x 100 kDa) is located on a crystallographic twofold axis.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Aldehyde Oxidoreductases/*chemistry; Amino Acid Sequence; Crystallization; Desulfovibrio/*enzymology; Iron-Sulfur Proteins/*analysis; Molecular Sequence Data; Molecular Weight; Molybdenum/*analysis; X-ray diffraction

Trabalho Operário e Novas Tecnologias de Produção: Alguns resultados de investigações internacionais [Workers labour and new production technologies: some results from international research] - António Moniz (University Library of Munich, Germany, 1993)
In the last two decades (70 and 80) there took place an intensive controversy in the field of Industrial and Work Sociology. There the topic of the study object of this scientific discipline is again discussed. This controversy, however, has a relatively different sense in comparison with the one that existed in early 60ies. The more recent one followed the increasing number of possibilities of electronical equipment for data processing at the same time its price is decreasing. In this article we try to give knowledge of the main elements that take part in such debate. It is also important to present the international character of the research developed in association with this discussion. It evolves a plurality of research teams that present, compare and synthesize the results of empirical studies that are applied for a wide variety of countries.
n/a
Keywords: data processing; industrial sociology; information technology; research

{Trabalho Operário e Novas Tecnologias de Produção: Alguns resultados de investigações internacionais [Workers labour and new production technologies: some results from international research]} - António Moniz (University Library of Munich, Germany, 1993)
In the last two decades (70 and 80) there took place an intensive controversy in the field of Industrial and Work Sociology. There the topic of the study object of this scientific discipline is again discussed. This controversy, however, has a relatively different sense in comparison with the one that existed in early 60ies. The more recent one followed the increasing number of possibilities of electronical equipment for data processing at the same time its price is decreasing. In this article we try to give knowledge of the main elements that take part in such debate. It is also important to present the international character of the research developed in association with this discussion. It evolves a plurality of research teams that present, compare and synthesize the results of empirical studies that are applied for a wide variety of countries.
n/a
Keywords: data processing; industrial sociology; information technology; research

Temperature-dependent proton NMR investigation of the electronic structure of the trinuclear iron cluster of the oxidized Desulfovibrio gigas ferredoxin II - Macedo, Anjos L.; Moura, Isabel; Moura, Jose J. G.; Legall, Jean; Huynh Boi, Hanh (Inorganic Chemistry, 1993)
n/a
doi: 10.1021/ic00059a013

Resonance Raman studies of nickel tetrathiolates and nickel-substituted rubredoxins and desulforedoxin - Huang, Yun Hua; Moura, Isabel; Moura, Jose J. G.; Legall, Jean; Park, Jae Bum; Adams, Michael W. W.; Johnson, Michael K. (Inorganic Chemistry, 1993)
n/a
doi: 10.1021/ic00056a012

Dipolar relaxation behaviour in poly(methyl methacrylate)/4-nitroaniline solid solutions - M. Dionísio; J. J. Moura Ramos; G. Williams (Polymer International, 1993)

Molecular motions in poly(vinyl acetate) and in poly(vinyl acetate)/p-nitroaniline mixtures - M. Dionísio; J. J. Moura Ramos; G. Williams (Polymer, 1993)

Preparation and liquid-crystalline properties of toluene-4-sulphonyl urethane of hydroxypropylcellulose - Godinho, Maria Helena; Borges, João Paulo; Bordado, João Carlos; Maria Teresa Cidade; Martins, Assis Farinha (Liquid Crystals, 1993)
A novel liquid-crystalline polymer, the toluene-4-sulphonyl urethane of hydroxypropylcellulose (TSUHPC), was prepared through chemical modification of hydroxypropylcellulose (HPC) of Mw = 60000 g mol−1. The resulting polymer was characterized by infrared spectroscopy, differential scanning calorimetry (DSC) and polarizing microscopy. It was found that thermotropic liquid crystal phases are formed between about 60°C and 110°C. Concentrated solutions of TSUHPC in acetone and N,N-dimethylacetamide exhibit cholesteric behaviour, at room temperature. When approaching the lyotropic mesophase to solid transition, either by cooling or by solvent evaporation, very interesting arborescent structures of a seemingly fractal nature may be observed, depending on the kinetics of the transition. A banded texture can be observed when the polymer is sheared near the transition to the isotropic phase.

Concepção de postos de trabalho em novos sistemas produtivos: o exemplo da robÓtica industrial [Job design in new productive systems: the exemple of industrial robotics] - António Moniz (University Library of Munich, Germany, 1993)
The design of jobs is defined and its different implications. These aspects must be taken into consideration when applied to new automated systems, once it can occur workers in-adaptations to certain type of activity and tasks. Other concepts that emerge from this are the mental workload, stress, work accidents, shift work, or the physical environment that can reveal to become determinant in the process of job design. That means also the organizational design. In this sense, the manufacturing, organizational and individual dimensions, are the most meaningful in the mentioned process of organizational design. Are analyzed different application cases of robotized systems and their social effects, mostly those that are related to the dimensions of working conditions. Are particularly analyzed the new risk situations that occur with the use of robotic systems. One concludes on the need to take into consideration qualitative variables in the definition and design of robotic cells, jobs and production systems. This consideration influences directly in the labor productivity, in such way that the development of these methodologies of analysis can be considered as integrating the processes of technological innovation in manufacturing.
n/a
Keywords: automated systems; industrial robotics; job design; organizational d; robotic cells; work conditions

Control of the spin state of the peroxidatic haem by calcium ions in cytochrome c peroxidase from Paracoccus denitrificans: A 1H NMR study - Prazeres, Susana; Moura, Isabel; Moura, José J. G.; Gilmour, Raymond; Goodhew, Celia F.; Pettigrew, Graham W. (Magnetic Resonance in Chemistry, 1993)
Cytochrome c peroxidase from Paracoccus denitrificans LMD 52.44 was recently identified. The enzyme contains two c-type haems: one is reducible physiologically by cytochrome c550 from the same organism or non-physiologically by ascorbate (high-potential haem) and the other by dithionite (low-potential haem). The enzymatically active form of the peroxidase is the half-reduced enzyme state, in which the high-potential haem is in the iron(II) state and the low-potential haem is in the iron(III) state. It was found that the two haems interact and that the enzyme binds calcium ions near the haem sites which are necessary to promote its activation. In the oxidized form, the high-potential haem is in a high-spin and the low-potential haem is in a low-spin state. The half-reduction of the enzyme with ascorbate-diaminodurol changes the high-potential haem (high-spin) into a low-spin state and the low-potential haem converts from a low- into a high-spin state. This high-spin conversion of the low-potential haem is induced by the presence of calcium ions. These processes of reduction and spin state change can be easily resolved in time by removing the calcium from the enzyme using EDTA, facilitating the observation of the intermediate form by NMR.
n/a
Keywords: 1H NMR; Calcium effect; Cytochrome c peroxidase; Haem spin state control; NMR; Paracoccus denitrificans

ELUCIDATION OF THE MULTIPLE EQUILIBRIA OF MALVIN IN AQUEOUS-SOLUTION BY ONE-DIMENSIONAL AND 2-DIMENSIONAL NMR - Santos, H.; Turner, D.L.; J. C. Lima; FIGUEIREDO, P; PINA, FS; Macanita, AL (Phytochemistry, 1993)
n/a
n/a

Oxovanadium(IV) and amino acids—VI. The systems glycylglycine and glycylglycylglycine + VO2+; a potentiometric and spectroscopic study - Pessoa, J. Costa; Luz, S. M.; Duarte, R.; Moura, J. J. G.; Gillard, R. D. (Polyhedron, 1993)
n/a
n/a

PHOTOCHEMICAL AND THERMAL-DEGRADATION OF ANTHOCYANIDINS - Furtado, P.; FIGUEIREDO, P; Dasneves, H. C.; Pina, F (Journal of Photochemistry and Photobiology a-Chemistry, 1993)
n/a
Times Cited: 52 Figueiredo, Paulo/A-2078-2012; Figueiredo, Paulo/A-2425-2012; Figueiredo, Paulo/A-2429-2012; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Figueiredo, Paulo/0000-0002-8340-9316; Pina, Fernando/0000-0001-8529-6848; 58

Resonance Raman study of sirohydrochlorin and siroheme in sulfite reductases from sulfate reducing bacteria - Underwood-Lemons, Theresa; Moura, Isabel; To Yue, Kwok (Biochimica et Biophysica Acta (BBA) - General Subjects, 1993)
n/a
n/a
Keywords: Enzyme; Hydroporphyrin; Isobacteriochlorin; Raman spectroscopy

SUBUNIT COMPOSITION, CRYSTALLIZATION AND PRELIMINARY CRYSTALLOGRAPHIC STUDIES OF THE DESULFOVIBRIO-GIGAS ALDEHYDE OXIDOREDUCTASE CONTAINING MOLYBDENUM AND 2FE-2S CENTERS - Romao, M. J.; Barata, B. A. S.; Archer, M.; Lobeck, K.; Moura, I.; Carrondo, M. A.; Legall, J.; Lottspeich, F.; Huber, R.; Moura, J. J. G. (European Journal of Biochemistry, 1993)
n/a
Times Cited: 24 Romao, Maria/A-4115-2013; Moura, Jose/D-6426-2013; REQUIMTE, SMB/M-5694-2013; Moura, Isabel/D-6339-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; Moura, Isabel/0000-0003-0971-4977; 24

Two-dimensional 1H NMR studies on Desulfovibrio gigas ferredoxins. Assignment of the iron-sulfur cluster cysteinyl ligand protons - Macedo, Anjos L.; Palma, P. Nuno; Moura, Isabel; Legall, Jean; Wray, Victor; Moura, José J. G. (Magnetic Resonance in Chemistry, 1993)
1D and 2D 1H NMR studies are reported on the oxidized and reduced [4Fe-4S] cluster of Desulfovibrio gigas ferredoxin I (Fdl). Several low-field contact shifted resonances (fast relaxing) are assigned to β-CH2 and α-CH coordinated cysteinyl residues. NOESY patterns (supported by 1D NOE experiments) resolves four pairs of geminal β-CH2 protons at low-field. The cluster ligands are assigned non-specifically to Cys8, Cys11, Cys14 and Cys50, based on the X-ray structural analysis available for the oligomeric form, FdII, that contains a single [3Fe-4S] cluster. It was indicated in this case that Cys11 is not bound to the trinuclear cluster but is tilted towards the solvent. The presence of four pairs of geminal β-CH2 protons for FdI unambiguously proves the occupancy of the fourth site of the [3Fe-4S] complex and implies the coordination of the Cys11 at the cluster. Analysis of the oxidized form of FdII, using the same methodology as described for FdI, supports the presence of three cysteinyl ligands in the [3Fe-4S] core. Further, the combined use of the X-ray coordinates enables the specific assignment of the three cysteinyl ligands of the cluster, extending a previous assignment of Cys50. In addition, very broad resonances were detected for the reduced form of FdII in the low-field region around 200 ppm and in the high field region around −80 ppm.
n/a
Keywords: 1H-NMR; 2D NMR; Desulfovibrio sp.; ferredoxins; iron-sulfur clusters; NMR; NOESY; TOCSY; [3Fe-4S] and [4Fe-4S] clusters

{Concepção de postos de trabalho em novos sistemas produtivos: o exemplo da robÓtica industrial [Job design in new productive systems: the exemple of industrial robotics]} - António Moniz (University Library of Munich, Germany, 1993)
The design of jobs is defined and its different implications. These aspects must be taken into consideration when applied to new automated systems, once it can occur workers in-adaptations to certain type of activity and tasks. Other concepts that emerge from this are the mental workload, stress, work accidents, shift work, or the physical environment that can reveal to become determinant in the process of job design. That means also the organizational design. In this sense, the manufacturing, organizational and individual dimensions, are the most meaningful in the mentioned process of organizational design. Are analyzed different application cases of robotized systems and their social effects, mostly those that are related to the dimensions of working conditions. Are particularly analyzed the new risk situations that occur with the use of robotic systems. One concludes on the need to take into consideration qualitative variables in the definition and design of robotic cells, jobs and production systems. This consideration influences directly in the labor productivity, in such way that the development of these methodologies of analysis can be considered as integrating the processes of technological innovation in manufacturing.
n/a
Keywords: automated systems; industrial robotics; job design; organizational d; robotic cells; work conditions

The photochemical reaction between uranyl-nitrate and azulene - Burrows, H. D.; Cardoso, A. C.; Formosinho, S. J.; Gil, Ampc; Miguel, M. D.; Barata, B.; Moura, J. J. G. (Journal of Photochemistry and Photobiology a-Chemistry, 1992)
On photolysis of solutions of azulene and uranyl nitrate in alcohols, a dark, amorphous precipitate is formed. Various analytical techniques show that this is a mixture of a uranium salt and an organic component, suggested to be polyazulene. The effects of various parameters on the yield of the product have been studied and it is found that oxygen facilitates the reaction. Electron spin resonance studies show that the product is paramagnetic, in agreement with the established ease of oxidation of polyazulene, and suggest that it is formed via electron transfer from azulene to excited uranyl ion, followed by successive dimerizations and deprotonations of radical cation intermediates.
Times Cited: 8

Partial purification and characterization of the first hydrogenase isolated from a thermophilic sulfate-reducing bacterium - Fauque, G.; Czechowski, M.; Berlier, Y. M.; Lespinat, P. A.; Legall, J.; Moura, J. J. (Biochem Biophys Res Commun, 1992)
A soluble [NiFe] hydrogenase has been partially purified from the obligate thermophilic sulfate-reducing bacterium Thermodesulfobacterium mobile. A 17% purification yield was obtained after four chromatographic steps and the hydrogenase presents a purity index (A398 nm/A277 nm) equal to 0.21. This protein appears to be 75% pure on SDS-gel electrophoresis showing two major bands of molecular mass around 55 and 15 kDa. This hydrogenase contains 0.6-0.7 nickel atom and 7-8 iron atoms per mole of enzyme and has a specific activity of 783 in the hydrogen uptake reaction, of 231 in the hydrogen production assay and of 84 in the deuterium-proton exchange reaction. The H2/HD ratio is lower than one in the D2-H+ exchange reaction. The enzyme is very sensitive to NO, relatively little inhibited by CO but unaffected by NO2-. The EPR spectrum of the native hydrogenase shows the presence of a [3Fe-4S] oxidized cluster and of a Ni(III) species.
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Chromatography, Gel; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hot Temperature; Hydrogenase/*isolation & purification/*metabolism; Kinetics; Thermodynamics

Direct spectroscopic evidence for the presence of a 6Fe cluster in an iron-sulfur protein isolated from Desulfovibrio desulfuricans (ATCC 27774) - Moura, I.; Tavares, P; Moura, J. J.; Ravi, N.; Huynh, B. H.; Liu, M. Y.; Legall, J. (J Biol Chem, 1992)
A novel iron-sulfur protein was purified from the extract of Desulfovibrio desulfuricans (ATCC 27774) to homogeneity as judged by polyacrylamide gel electrophoresis. The purified protein is a monomer of 57 kDa molecular mass. It contains comparable amounts of iron and inorganic labile sulfur atoms and exhibits an optical spectrum typical of iron-sulfur proteins with maxima at 400, 305, and 280 nm. Mossbauer data of the as-isolated protein show two spectral components, a paramagnetic and a diamagnetic, of equal intensity. Detailed analysis of the paramagnetic component reveals six distinct antiferromagnetically coupled iron sites, providing direct spectroscopic evidence for the presence of a 6Fe cluster in this newly purified protein. One of the iron sites exhibits parameters (delta EQ = 2.67 +/- 0.03 mm/s and delta = 1.09 +/- 0.02 mm/s at 140 K) typical for high spin ferrous ion; the observed large isomer shift indicates an iron environment that is distinct from the tetrahedral sulfur coordination commonly observed for the iron atoms in iron-sulfur clusters and is consistent with a penta- or hexacoordination containing N and/or O ligands. The other five iron sites are most probably high spin ferric. Three of them show parameters characteristic for tetrahedral sulfur coordination. In correlation with the EPR spectrum of the as-purified protein which shows a resonance signal at g = 15.3 and a group of signals between g = 9.8 and 5.4, this 6Fe cluster is assigned to an unusual spin state of 9/2 with zero field splitting parameters D = -1.3 cm-1 and E/D = 0.062. Other EPR signals attributable to minor impurities are also observed at the g = 4.3 and 2.0 regions. The diamagnetic Mossbauer component represents a second iron cluster, which, upon reduction with dithionite, displays an intense S = 1/2 EPR signal with g values at 2.00, 1.83, and 1.31. In addition, an EPR signal of the S = 3/2 type is also observed for the dithionite-reduced protein.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Amino Acid Sequence; Bacterial Proteins; Desulfovibrio/*metabolism; Electron Spin Resonance Spectroscopy; Electrophoresis, Polyacrylamide Gel; Iron-Sulfur Proteins/chemistry/*isolation & purification; Iron/chemistry; Molecular Sequence Data

Mossbauer characterization of the tetraheme cytochrome c3 from Desulfovibrio baculatus (DSM 1743). Spectral deconvolution of the heme components - Ravi, N.; Moura, I.; Costa, C.; Teixeira, M.; Legall, J.; Moura, J. J.; Huynh, B. H. (Eur J Biochem, 1992)
Mossbauer spectroscopy was used to study the tetraheme cytochrome c3 from Desulfovibrio baculatus (DSM 1743). Samples with different degrees of reduction were prepared using a redoxtitration technique. In the reduced cytochrome c3, all four hemes are reduced and exhibit diamagnetic Mossbauer spectra typical for low-spin ferrous hemes (S = 0). In the oxidized protein, the hemes are low-spin ferric (S = 1/2) and exhibit overlapping magnetic Mossbauer spectra. A method of differential spectroscopy was applied to deconvolute the four overlapping heme spectra and a crystal-field model was used for data analysis. Characteristic Mossbauer spectral components for each heme group are obtained. Hyperfine and crystal-field parameters for all four hemes are determined from these deconvoluted spectra.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Cytochrome c Group/*chemistry; Desulfovibrio/*enzymology; Heme/chemistry; Oxidation-Reduction; Protein Conformation; Spectroscopy, Mossbauer

Mossbauer study of the native, reduced and substrate-reacted Desulfovibrio gigas aldehyde oxido-reductase - Barata, B. A.; Liang, J.; Moura, I.; Legall, J.; Moura, J. J.; Huynh, B. H. (Eur J Biochem, 1992)
The Desulfovibrio gigas aldehyde-oxido-reductase contains molybdenum and iron-sulfur clusters. Mossbauer spectroscopy was used to characterize the iron-sulfur clusters. Spectra of the enzyme in its oxidized, partially reduced and benzaldehyde-reacted states were recorded at different temperatures and applied magnetic fields. All the iron atoms in D. gigas aldehyde oxido-reductase are organized as [2Fe-2S] clusters. In the oxidized enzyme, the clusters are diamagnetic and exhibit a single quadrupole doublet with parameters (delta EQ = 0.62 +/- 0.02 mm/s and delta = 0.27 +/- 0.01 mm/s) typical for the [2Fe-2S]2+ state. Mossbauer spectra of the reduced clusters also show the characteristics of a [2Fe-2S]1+ cluster and can be explained by a spin-coupling model proposed for the [2Fe-2S] cluster where a high-spin ferrous ion (S = 2) is antiferromagnetically coupled to a high-spin ferric ion (S = 5/2) to form a S = 1/2 system. Two ferrous sites with different delta EQ values (3.42 mm/s and 2.93 mm/s at 85 K) are observed for the reduced enzyme, indicating the presence of two types of [2Fe-2S] clusters in the D. gigas enzyme. Taking this observation together with the re-evaluated value of iron content (3.5 +/- 0.1 Fe/molecule), it is concluded that, similar to other Mo-hydroxylases, the D. gigas aldehyde oxido-reductase also contains two spectroscopically distinguishable [2Fe-2S] clusters.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Aldehyde Oxidoreductases/*chemistry; Desulfovibrio/*enzymology; Dithionite/chemistry; Electron Spin Resonance Spectroscopy; Iron/analysis; Molybdenum/analysis; Oxidation-Reduction; Spectroscopy, Mossbauer; Substrate Specificity

REACTIONS OF HYDROXYLAMINES WITH ETHYL CYANOFORMATE - PREPARATION OF AMINONITRONES AND THEIR SYNTHETIC APPLICATIONS - Branco, P. S.; Prabhakar, S.; A. M. Lobo; Williams, D. J. (TETRAHEDRON, 1992)
n/a
n/a

The nickel site in active Desulfovibrio baculatus [NiFeSe] hydrogenase is diamagnetic. Multifield saturation magnetization measurement of the spin state of Ni(II) - Wang, C. P.; Franco, R.; Moura, J. J.; Moura, I.; Day, E. P. (J Biol Chem, 1992)
The magnetic properties of the nickel(II) site in active Desulfovibrio baculatus (DSM 1743) [NiFeSe] hydrogenase have been measured using the multifield saturation magnetization technique. The periplasmic [NiFeSe] hydrogenase was isolated from bacteria grown in excess selenium in the presence of 57Fe. Saturation magnetization data were collected at three fixed fields (1.375, 2.75, 5.5 tesla) over the temperature range from 2 to 100 K. Mossbauer and EPR spectroscopies were used to characterize the magnetic state of the two [4Fe-4S] clusters of the enzyme and to quantitate the small amounts of iron impurities present in the sample. The nickel(II) site was found to be diamagnetic (low spin, S = 0). In combination with recent results from extended x-ray absorption fine structure studies, this magnetic state indicates that the nickel(II) site of active D. baculatus [NiFeSe] hydrogenase is five-coordinate.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: *Magnetics; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogenase/*chemistry; Nickel/*chemistry; Spectroscopy, Mossbauer

CHARGE EFFECTS ON THE PHOTOCHEMISTRY OF THE CO(EDTA) .1. SYSTEM IN THE PRESENCE OF POLYAMMONIUM MACROCYCLIC RECEPTORS - Pina, F; A. J. Parola; Bencini, A; Micheloni, M.; Manfrin, M. F.; Moggi, L. (Inorganica Chimica Acta, 1992)
The effects of polyammonium macrocycles on the spectroscopic and photochemical properties of the Co(EDTA)- . I- ion-pair have been investigated. The addition of a macrocycle to aqueous solutions containing Co(EDTA)- and I- causes an increase of the absorbance in the region of the ion-pair charge-transfer band, as well as an increase of the quantum yield for the intramolecular photooxidation reduction of the ion-pair. Both these effects are mainly, if not only, due to an increase of the association constant between Co(EDTA)- and I-, caused by the positive charge of the macrocycle bound to the complex. On the contrary no change was observed on the intrinsic photoreactivity of the excited ion-pair. This last result is discussed in comparison with the effects already observed on the ligand photodissociation of MC excited states of Co(III) cyanide complexes.
ISI Document Delivery No.: JF612Times Cited: 1 Cited Reference Count: 15 Pina, f parola, aj bencini, a micheloni, m manfrin, mf moggi, l Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Elsevier science sa lausanne Lausanne 1

PHOTOCHEMISTRY OF THE ADDUCT BETWEEN CO(CN)5H2O 2- AND THE POLYAMMONIUM MACROCYCLIC RECEPTOR 32 ANE-N8 - EVIDENCE FOR THE SUPRAMOLECULAR STRUCTURE - A. J. Parola; Pina, F (Journal of Photochemistry and Photobiology a-Chemistry, 1992)
The photochemistry of aqueous solutions of [Co(CN)5H2O]2- in the presence of the polyammonium macrocyclic receptor [32]ane-N8H88+ was studied. The quantum yield for cyanide release in free [Co(CN)5H2O]2- (PHI = 0.003 at 313 nm, pH 1.5) is reduced approximately threefold in the presence of the protonated macrocycle, which provides evidence for the formation of a supramolecular structure. Further evidence for the supramolecular structure is obtained from the thermal anation of [Co(CN)5H2O]2- with Br- (40-degrees-C, pH 1.0), the rate of which is increased in the presence of [32]ane-N8H88+, suggesting that the ligand water is not involved in hydrogen bonds with the macrocycle. These results are interpreted in terms of possible supramolecular structures.
ISI Document Delivery No.: JD486Times Cited: 5 Cited Reference Count: 13 Parola, aj pina, f Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Elsevier science sa lausanne Lausanne 1

Assignment of the redox potentials to the four haems in Desulfovibrio vulgaris cytochrome c3 by 2D-NMR - Salgueiro, C.A.; Turner, David L.; Santos, Helena; Legall, Jean; Xavier, António V. (FEBS Letters, 1992)
Using 2D-NMR the four haems of Desulfovibrio vulgaris (Hildenborough) cytochromes, within the X-ray structure were fully cross-assigned according to their redox potential. The strategy used was based on a complete network of chemical exchange connectivities between the NMR signals obtained for all oxidation levels to the corresponding ones in the fully reduced spectrum [1992, Eur. J. Biochem., in press]. This unequivocal cross-assignment disagrees within earlier results obtained for the similar protein from Desulfovibrio vulgaris (Miyazaki F.) [1991, FEBS Lett. 285, 149–151]

Structural studies of Desulfovibrio vulgaris ferrocytochrome c3 by two-dimensional NMR - Turner, David L.; Salgueiro, C.A.; Legall, Jean; Xavier, António V. (European Journal of Biochemistry, 1992)
Two-dimensional NMR has been used to make specific assignments for the four haems in Desulfovibrio vulgaris (Hildenborough) ferrocytochrome c3 and to determine their haem core architecture. The NMR signals from the haem protons were assigned according to type using two-dimensional NMR experiments which led to four sets of signals, one for each of the haems. Specific assignments were obtained by calculating the ring current shifts which arise from other haems and aromatic residues. Observation of interhaem NOEs confirmed the assignments and established that the relative orientation of the haems is identical to that found in the crystal structure of D. vulgaris (Miyazaki F.) ferricytochrome c3. Assignments were also made for all the aromatic residues except for the haem ligands and F20, which is shifted under the main envelope of signals. The NOEs observed between these aromatic protons and haem protons confirm the similarity between the structures in solution and in the crystal. The assignments reported here are the basis for the cross-assignments of the four microscopic haem redox potentials to specific haems in the protein structure.

CRYSTAL-STRUCTURE ANALYSIS, REFINEMENT AND ENZYMATIC-REACTION MECHANISM OF N-CARBAMOYLSARCOSINE AMIDOHYDROLASE FROM ARTHROBACTER SP AT 2.0-ANGSTROM RESOLUTION - Romao, M. J.; Turk, D.; GomisRuth, F. X.; Huber, R.; Schumacher, G.; Mollering, H.; Russmann, L. (Journal of Molecular Biology, 1992)
n/a
Times Cited: 32 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 34

DIRECT SPECTROSCOPIC EVIDENCE FOR THE PRESENCE OF A 6FE CLUSTER IN AN IRON-SULFUR PROTEIN ISOLATED FROM DESULFOVIBRIO-DESULFURICANS (ATCC-27774) - Moura, I.; Tavares, P; Moura, J. J. G.; Ravi, N.; Huynh, B. H.; Liu, M. Y.; Legall, J. (Journal Of Biological Chemistry, 1992)
A novel iron-sulfur protein was purified from the extract of Desulfovibrio desulfuricans (ATCC 27774) to homogeneity as judged by polyacrylamide gel electrophoresis. The purified protein is a monomer of 57 kDa molecular mass. It contains comparable amounts of iron and inorganic labile sulfur atoms and exhibits an optical spectrum typical of iron-sulfur proteins with maxima at 400, 305, and 280 nm. Mossbauer data of the as-isolated protein show two spectral components, a paramagnetic and a diamagnetic, of equal intensity. Detailed analysis of the paramagnetic component reveals six distinct antiferromagnetically coupled iron sites, providing direct spectroscopic evidence for the presence of a 6Fe cluster in this newly purified protein. One of the iron sites exhibits parameters (DELTA-E(Q) = 2.67 +/- 0.03 mm/s and delta = 1.09 +/- 0.02 mm/s at 140 K) typical for high spin ferrous ion; the observed large isomer shift indicates an iron environment that is distinct from the tetrahedral sulfur coordination commonly observed for the iron atoms in iron-sulfur clusters and is consistent with a penta- or hexacoordination containing N and/or O ligands. The other five iron sites are most probably high spin ferric. Three of them show parameters characteristic for tetrahedral sulfur coordination. In correlation with the EPR spectrum of the as-purified protein which shows a resonance signal at g = 15.3 and a group of signals between g = 9.8 and 5.4, this 6Fe cluster is assigned to an unusual spin state of 9/2 with zero field splitting parameters D = -1.3 cm-1 and E/D = 0.062. Other EPR signals attributable to minor impurities are also observed at the g = 4.3 and 2.0 regions. The diamagnetic Mossbauer component represents a second iron cluster, which, upon reduction with dithionite, displays an intense S = 1/2 EPR signal with g values at 2.00, 1.83, and 1.31. In addition, an EPR signal of the S = 3/2 type is also observed for the dithionite-reduced protein.
n/a

ESCHERICHIA-COLI DIHYDRODIPICOLINATE SYNTHASE - IDENTIFICATION OF THE ACTIVE-SITE AND CRYSTALLIZATION - Laber, B.; GomisRuth, F. X.; Romao, M. J.; Huber, R. (Biochemical Journal, 1992)
n/a
Times Cited: 64 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 2 67

NMR and EPR studies on a monoheme cytochrome c550 isolated from Bacillus halodenitrificans - Saraiva, Lígia M.; Denariaz, Gerard; Liu, Ming- Y.; Payne, William J.; Legall, Jean; Moura, Isabel (European Journal of Biochemistry, 1992)
A c-type monoheme ferricytochrome c550 (9.6 kDa) was isolated from cells of Bacillus halodenitrificans sp.nov., grown anaerobically as a denitrifier. The visible absorption spectrum indicates the presence of a band at 695 nm characteristic of heme–methionine coordination. The mid-point redox potential was determined at several pH values by visible spectroscopy. The redox potential at pH 7.6 is 138 mV. When studied by 1H-NMR spectroscopy as a function of pH, the spectrum shows a pH dependence with pKa values of 6.0 and 11.0. According to these pKa values, three forms designated as I, II and III can be attributed to cytochrome c550. The first pKa is probably associated with protonation of the propionate groups. The second pKa value introduces a larger effect in the 1H-NMR spectrum and is probably due to the ionisation of the axial histidine. Studies of temperature variation of the 1H-NMR spectra for both the ferrous and ferri forms of the cytochrome were performed. Heme meso protons, the heme methyl groups, the thioether protons, two protons from a propionate and the methylene protons from the axial methionine were identified in the reduced form. The heme methyl resonances of the ferri form were also assigned. EPR spectroscopy was also used to probe the ferric heme environment. A signal at gmax∼ 3.5 at pH 7.5 was observed indicating an almost axial heme environment. At higher pH values the signal at gmax∼ 3.5 converts mainly to a signal at g∼ 2.96. The pKa associated with this change is around 11.3. The N-terminal sequence of this cytochrome was determined and compared with known amino acid sequences of other cytochromes.
n/a

The photochemical reaction between uranyl nitrate and azulene - Burrows, Hugh D.; Cardoso, Augusto C.; Formosinho, Sebastião J.; Gil, Ana M. P. C.; Miguel, Maria da Graça M.; Barata, Belamino; J.G. Moura, José (Journal of Photochemistry and Photobiology A: Chemistry, 1992)
n/a
n/a

PHOTOCHEMISTRY OF 2-(2-FURYL)-BENZIMIDAZOLE (FUBERIDAZOLE) - Melo, MJ; Pina, F; Macanita, AL; Melo, EC; Herrmann, C.; Forster, R.; Koch, H.; Wamhoff, H. (Zeitschrift Fur Naturforschung Section B-a Journal of Chemical Sciences, 1992)
n/a
Times Cited: 7 Melo, Eurico/C-1297-2008; Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; Macanita, Antonio/H-9284-2012; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; Macanita, Antonio/0000-0003-0976-6654; 7

Spectroscopic studies on APS reductase isolated from the hyperthermophilic sulfate-reducing archaebacterium Archaeglobus fulgidus - Lampreia, J.; Fauque, G.; Speich, N.; Dahl, C.; Moura, I.; Truper, H. G.; Moura, J. J. (Biochem Biophys Res Commun, 1991)
Adenylyl sulfate (APS) reductase, the key enzyme of the dissimilatory sulfate respiration, catalyzes the reduction of APS (the activated form of sulfate) to sulfite with release of AMP. A spectroscopic study was carried out with the APS reductase purified from the extremely thermophilic sulfate-reducing archaebacterium Archaeoglobus fulgidus DSM 4304. Combined ultraviolet/visible spectroscopy and low temperature electron paramagnetic resonance (EPR) studies were used in order to characterize the active centers and the reactivity towards AMP and sulfite of this enzyme. The A. fulgidus APS reductase is an iron-sulfur flavoprotein containing two distinct [4Fe-4S] clusters (Centers I and II) very similar to the homologous enzyme from Desulfovibrio gigas. Center I, which has a high redox potential, is reduced by AMP and sulfite, and Center II has a very negative redox potential.
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: *Oxidoreductases Acting on Sulfur Group Donors; Archaea/*enzymology; Binding Sites; Electron Spin Resonance Spectroscopy; Hot Temperature; Oxidation-Reduction; Oxidoreductases/chemistry/isolation & purification/*metabolism; Spectrophotometry; Sulfates/metabolism

Spectroscopic studies of cobalt and nickel substituted rubredoxin and desulforedoxin - Moura, I.; Teixeira, M.; Legall, J.; Moura, J. J. (J Inorg Biochem, 1991)
The single iron site of rubredoxin was replaced by nickel and cobalt. The near-infrared/visible/UV spectra of these metal derivatives show ligand-field transitions and charge-transfer bands which closely resemble those of simple tetrathiolate complexes, indicating a tetrahedral arrangement of the sulfur cysteinyl ligands around the metal core. The 1H NMR spectra of the nickel and cobalt derivatives reveal extremely low-field contact shifted resonances of one proton intensity assigned to beta-CH2 and alpha-CH cysteinyl protons. Other well resolved resonances shifted out of the main protein spectral envelope are also observed and probably arise from contact plus pseudocontact shift mechanisms. Rubredoxins from different sulfate reducers were metal substituted and assignments of aliphatic protons are tentatively proposed, taking advantage of the amino acid sequence homologies. The present data is promising in terms of structural analysis of the coordination sphere of the metal core. It was also shown that replacement of the iron atom of desulforedoxin, a close analogue of rubredoxin, by cobalt and nickel was possible.
0162-0134 (Print)0162-0134 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Amino Acid Sequence; Circular Dichroism; Cobalt/*chemistry; Desulfovibrio/*chemistry; Electron Spin Resonance Spectroscopy; Iron-Sulfur Proteins/*chemistry; Magnetic Resonance Spectroscopy; Molecular Sequence Data; Nickel/*chemistry; Rubredoxins/*chemistry; Sequence Homology, Nucleic Acid

Structural and functional approach toward a classification of the complex cytochrome c system found in sulfate-reducing bacteria - Moura, J. J.; Costa, C.; Liu, M. Y.; Moura, I.; Legall, J. (Biochim Biophys Acta, 1991)
Following the discovery of the tetraheme cytochrome c3 in the strict anaerobic sulfate-reducing bacteria (Postgate, J.R. (1954) Biochem. J. 59, xi; Ishimoto et al. (1954) Bull. Chem. Soc. Japan 27, 564-565), a variety of c-type cytochromes (and others) have been reported, indicating that the array of heme proteins in these bacteria is complex. We are proposing here a tentative classification of sulfate- (and sulfur-) reducing bacteria cytochromes c based on: number of hemes per monomer, heme axial ligation, heme spin state and primary structures (whole or fragmentary). Different and complementary spectroscopic tools have been used to reveal the structural features of the heme sites.
0006-3002 (Print)0006-3002 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.Review
Keywords: Amino Acid Sequence; Binding Sites; Cytochrome c Group/*classification; Desulfovibrio/*enzymology; Heme/*chemistry; Molecular Sequence Data

Simulation of the electrochemical behavior of multi-redox systems. Current potential studies on multiheme cytochromes - Moreno, C.; Campos, A.; Teixeira, M.; Legall, J.; Montenegro, M. I.; Moura, I.; Van Dijk, C.; Moura, J. G. (Eur J Biochem, 1991)
The direct unmediated electrochemical response of the tetrahemic cytochrome c3 isolated from sulfate reducers Desulfovibrio baculatus (DSM 1743) and D. vulgaris (strain Hildenborough), was evaluated using different electrode systems [graphite (edge cut), gold, semiconductor (InO2) and mercury)] and different electrochemical methods (cyclic voltammetry and differential pulse voltammetry). A computer program was developed for the theoretical simulation of a complete cyclic voltammetry curve, based on the method proposed by Nicholson and Shain [Nicholson, R.S. & Shain, I. (1964) Anal. Chem. 36, 706-723], using the Gauss-Legendre method for calculation of the integral equations. The experimental data obtained for this multi-redox center protein was deconvoluted in to the four redox components using theoretically generated cyclic voltammetry curves and the four mid-point reduction potentials determined. The pH dependence of the four reduction potentials was evaluated using the deconvolution method described.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Carbon; Cytochrome c Group/*chemistry; Desulfovibrio/enzymology; Electrochemistry/methods; Hydrogen-Ion Concentration; Mathematics; Mercury; Oxidation-Reduction; Software

Information from e.p.r. spectroscopy on the iron-sulphur centres of the iron-molybdenum protein (aldehyde oxidoreductase) of Desulfovibrio gigas - Bray, R. C.; Turner, N. A.; Legall, J.; Barata, B. A.; Moura, J. J. (Biochem J, 1991)
E.p.r. spectra of reduced iron-sulphur centres of the aldehyde oxidoreductase (iron-molybdenum protein) of Desulfovibrio gigas were recorded at X-band and Q-band frequencies and simulated. Results are consistent with the view that only two types of [2Fe-2S] clusters are present, as in eukaryotic molybdenum-containing hydroxylases. The data indicate the Fe/SI centre to be very similar, and the Fe/SII centre somewhat similar, to these centres in the eukaryotic enzymes.
0264-6021 (Print)0264-6021 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Aldehyde Oxidoreductases/*chemistry/isolation & purification; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Iron-Sulfur Proteins/*chemistry/isolation & purification; Molybdoferredoxin/*chemistry

2-ACYL THIAZOLIUM SALTS AS SELECTIVE AGENTS FOR THE O-ACYLATION OF AROMATIC HYDROXYLAMINES - Ferreira, LM; A. M. Lobo; Prabhakar, S.; MARCELOCURTO, MJ; Rzepa, H. S.; YI, MY (JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1991)
n/a
n/a

APPLICATION OF CO-59 NMR TO THE INVESTIGATION OF INTERACTIONS BETWEEN COBALT SEPULCHRATE AND VARIOUS COUNTERIONS - J. Sotomayor; Santos, H.; Pina, F (Canadian Journal of Chemistry-Revue Canadienne De Chimie, 1991)
n/a
Times Cited: 10 Santos, Helena/B-9141-2011; Pina, Fernando/C-8161-2011; Sotomayor, Joao/D-8103-2013; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; Sotomayor, Joao/0000-0002-4589-0591; 10

Direct evidence of the metal-free nature of sirohydrochlorin in desulfoviridin - Lai, K. K.; Moura, Isabel; Liu, Ming Y.; Legall, Jean; To Yue, Kwok (Biochimica et Biophysica Acta (BBA) - Bioenergetics, 1991)
n/a
n/a
Keywords: Raman spectroscopy; Sirohydrochlorin; Sulfite reductase

A long-range adaptive controller for robot manipulators - Coito, F.J.; Lemos, J. M. (The International journal of robotics research, 1991)
n/a
n/a

The active centers of adenylylsulfate reductase from Desulfovibrio gigas. Characterization and spectroscopic studies - Lampreia, J.; Moura, I.; Teixeira, M.; Peck, H. D., Jr.; Legall, J.; Huynh, B. H.; Moura, J. J. (Eur J Biochem, 1990)
In order to utilize sulfate as the terminal electron acceptor, sulfate-reducing bacteria are equipped with a complex enzymatic system in which adenylylsulfate (AdoPSO4) reductase plays one of the major roles, reducing AdoPSO4 (the activated form of sulfate) to sulfite, with release of AMP. The enzyme has been purified to homogeneity from the anaerobic sulfate reducer Desulfovibrio gigas. The protein is composed of two non-identical subunits (70 kDa and 23 kDa) and is isolated in a multimeric form (approximately 400 kDa). It is an iron-sulfur, flavin-containing protein, with one FAD moiety, eight iron atoms and a minimum molecular mass of 93 kDa. Low-temperature EPR studies were performed to characterize its redox centers. In the native state, the enzyme showed an almost isotropic signal centered at g = 2.02 and only detectable below 20 K. This signal represented a minor species (0.10-0.25 spins/mol) and showed line broadening in the enzyme isolated from 57Fe-grown cells. Addition of sulfite had a minor effect on the EPR spectrum, but caused a major decrease in the visible region of the optical spectrum (around 392 nm). Further addition of AMP induced only a minor change in the visible spectrum whereas major changes were seen in the EPR spectrum; the appearance of a rhombic signal at g values 2.096, 1.940 and 1.890 (reduced Fe-S center I) observable below 30 K and a concomitant decrease in intensity of the g = 2.02 signal were detected. Effects of chemical reductants (ascorbate, H2/hydrogenase-reduced methyl viologen and dithionite) were also studied. A short time reduction with dithionite (15 s) or reduction with methyl viologen gave rise to the full reduction of center I (with slightly modified g values at 2.079, 1.939 and 1.897), and the complete disappearance of the g = 2.02 signal. Further reduction with dithionite produces a very complex EPR spectrum of a spin-spin-coupled nature (observable below 20 K), indicating the presence of at least two iron-sulfur centers, (centers I and II). Mossbauer studies on 57Fe-enriched D. gigas AdoPSO4 reductase demonstrated unambiguously the presence of two 4Fe clusters. Center II has a redox potential less than or equal to 400 mV and exhibits spectroscopic properties that are characteristic of a ferredoxin-type [4Fe-4S] cluster. Center I exhibits spectra with atypical Mossbauer parameters in its reduced state and has a midpoint potential around 0 mV, which is distinct from that of a ferredoxin-type [4Fe-4S] cluster, suggesting a different structure and/or a distinct cluster-ligand environment.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: *Oxidoreductases Acting on Sulfur Group Donors; Adenosine Monophosphate/pharmacology; Binding Sites; Desulfovibrio/*enzymology; Dithionite/pharmacology; Electron Spin Resonance Spectroscopy; Iron-Sulfur Proteins/analysis; Oxidation-Reduction; Oxidoreductases/antagonists & inhibitors/*isolation & purification; Spectrophotometry, Ultraviolet; Spectroscopy, Mossbauer; Sulfites/pharmacology; Temperature

Purification and characterization of desulfoferrodoxin. A novel protein from Desulfovibrio desulfuricans (ATCC 27774) and from Desulfovibrio vulgaris (strain Hildenborough) that contains a distorted rubredoxin center and a mononuclear ferrous center - Moura, I.; Tavares, P; Moura, J. J.; Ravi, N.; Huynh, B. H.; Liu, M. Y.; Legall, J. (J Biol Chem, 1990)
A new type of non-heme iron protein was purified to homogeneity from extracts of Desulfovibrio desulfuricans (ATCC 27774) and Desulfovibrio vulgaris (strain Hildenborough). This protein is a monomer of 16-kDa containing two iron atoms per molecule. The visible spectrum has maxima at 495, 368, and 279 nm and the EPR spectrum of the native form shows resonances at g = 7.7, 5.7, 4.1 and 1.8 characteristic of a high-spin ferric ion (S = 5/2) with E/D = 0.08. Mossbauer data indicates the presence of two types of iron: an FeS4 site very similar to that found in desulforedoxin from Desulfovibrio gigas and an octahedral coordinated high-spin ferrous site most probably with nitrogen/oxygen-containing ligands. Due to this rather unusual combination of active centers, this novel protein is named desulfoferrodoxin. Based on NH2-terminal amino acid sequence determined so far, the desulfoferrodoxin isolated from D. desulfuricans (ATCC 27774) appears to be a close analogue to a recently discovered gene product from D. vulgaris (Brumlik, M.J., and Voordouw, G. (1989) J. Bacteriol. 171, 49996-50004), which was suggested to be a rubredoxin oxidoreductase. However, reduced pyridine nucleotides failed to reduce the desulforedoxin-like center of this new protein.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Amino Acid Sequence; Amino Acids/analysis; Desulfovibrio/*analysis; Electron Spin Resonance Spectroscopy; Ferredoxins/chemistry/*isolation & purification; Iron/analysis; Molecular Sequence Data; Molecular Weight; Oxidation-Reduction; Peptide Fragments/chemistry; Spectrum Analysis

Regulation of the hexaheme nitrite/nitric oxide reductase of Desulfovibrio desulfuricans, Wolinella succinogenes and Escherichia coli. A mass spectrometric study - Costa, C.; Macedo, A.; Moura, I.; Moura, J. J.; Legall, J.; Berlier, Y.; Liu, M. Y.; Payne, W. J. (FEBS Lett, 1990)
Dissimilatory nitrite reduction, carried out by hexaheme proteins, gives ammonia as the final product. Representatives of this enzyme group from 3 bacterial species can also reduce NO to either ammonia or N2O. The redox regulation of the nitrite/nitric oxide activities is discussed in the context of the denitrifying pathway.
0014-5793 (Print)0014-5793 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Ascorbic Acid/metabolism; Bacteroidaceae/*enzymology; Desulfovibrio/*enzymology; Dithionite/metabolism; Escherichia coli/*enzymology; Kinetics; Mass Spectrometry; NADP/metabolism; Nitric Oxide/metabolism; Nitrite Reductases/*metabolism; Oxidoreductases/*metabolism

Hexaheme nitrite reductase from Desulfovibrio desulfuricans. Mossbauer and EPR characterization of the heme groups - Costa, C.; Moura, J. J.; Moura, I.; Liu, M. Y.; Peck, H. D., Jr.; Legall, J.; Wang, Y. N.; Huynh, B. H. (J Biol Chem, 1990)
Mossbauer and EPR spectroscopy were used to characterize the heme prosthetic groups of the nitrite reductase isolated from Desulfovibrio desulfuricans (ATCC 27774), which is a membrane-bound multiheme cytochrome capable of catalyzing the 6-electron reduction of nitrite to ammonia. At pH 7.6, the as-isolated enzyme exhibited a complex EPR spectrum consisting of a low-spin ferric heme signal at g = 2.96, 2.28, and 1.50 plus several broad resonances indicative of spin-spin interactions among the heme groups. EPR redox titration studies revealed yet another low-spin ferric heme signal at g = 3.2 and 2.14 (the third g value was undetected) and the presence of a high-spin ferric heme. Mossbauer measurements demonstrated further that this enzyme contained six distinct heme groups: one high-spin (S = 5/2) and five low-spin (S = 1/2) ferric hemes. Characteristic hyperfine parameters for all six hemes were obtained through a detailed analysis of the Mossbauer spectra. D. desulfuricans nitrite reductase can be reduced by chemical reductants, such as dithionite or reduced methyl viologen, or by hydrogenase under hydrogen atmosphere. Addition of nitrite to the fully reduced enzyme reoxidized all five low-spin hemes to their ferric states. The high-spin heme, however, was found to complex NO, suggesting that the high-spin heme could be the substrate binding site and that NO could be an intermediate present in an enzyme-bound form.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy/methods; Heme/*metabolism; NADH, NADPH Oxidoreductases/*metabolism; Nitrite Reductases/isolation & purification/*metabolism; Oxidation-Reduction; Spectrum Analysis

Purification and characterization of bisulfite reductase (desulfofuscidin) from Desulfovibrio thermophilus and its complexes with exogenous ligands - Fauque, G.; Lino, A. R.; Czechowski, M.; Kang, L.; Dervartanian, D. V.; Moura, J. J.; Legall, J.; Moura, I. (Biochim Biophys Acta, 1990)
A dissimilatory bisulfite reductase has been purified from a thermophilic sulfate-reducing bacterium Desulfovibrio thermophilus (DSM 1276) and studied by EPR and optical spectroscopic techniques. The visible spectrum of the purified bisulfite reductase exhibits absorption maxima at 578.5, 392.5 and 281 nm with a weak band around 700 nm. Photoreduction of the native enzyme causes a decrease in absorption at 578.5 nm and a concomitant increase in absorption at 607 nm. When reduced, the enzyme reacts with cyanide, sulfite, sulfide and carbon monoxide to give stable complexes. The EPR spectrum of the native D. thermophilus bisulfite reductase shows the presence of a high-spin ferric signal with g values at 7.26, 4.78 and 1.92. Upon photoreduction the high-spin ferric heme signal disappeared and a typical 'g = 1.94' signal of [4Fe-4S] type cluster appeared. Chemical analyses show that the enzyme contains four sirohemes and eight [4Fe-4S] centers per mol of protein. The molecular mass determined by gel filtration was found to be 175 kDa. On SDS-gel electrophoresis the enzyme presents a main band of 44 to 48 kDa. These results suggest that the bisulfite reductase contains probably one siroheme and two [4Fe-4S] centers per monomer. The dissimilatory bisulfite reductase from D. thermophilus presents some homologous properties with desulfofuscidin, the bisulfite reductase isolated from Thermodesulfobacterium commune (Hatchikian, E.C. and Zeikus, J.G. (1983) J. Bacteriol. 153, 1211-1220).
0006-3002 (Print)0006-3002 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov't
Keywords: Amino Acids/analysis; Desulfovibrio/*enzymology/growth & development; Electron Spin Resonance Spectroscopy; Kinetics; Ligands; Macromolecular Substances; Molecular Weight; Oxidoreductases Acting on Sulfur Group Donors/*isolation &; Oxidoreductases/*isolation & purification; Protein Binding; purification/metabolism; Species Specificity; Spectrophotometry

The iron-sulfur centers of the soluble [NiFeSe] hydrogenase, from Desulfovibrio baculatus (DSM 1743). EPR and Mossbauer characterization - Teixeira, M.; Moura, I.; Fauque, G.; Dervartanian, D. V.; Legall, J.; Peck, H. D., Jr.; Moura, J. J.; Huynh, B. H. (Eur J Biochem, 1990)
The soluble (cytoplasmic plus periplasmic) Ni/Fe-S/Se-containing hydrogenase from Desulfovibrio baculatus (DSM 1743) was purified from cells grown in an 57Fe-enriched medium, and its iron-sulfur centers were extensively characterized by Mossbauer and EPR spectroscopies. The data analysis excludes the presence of a [3Fe-4S] center, either in the native (as isolated) or in the hydrogen-reduced states. In the native state, the non-heme iron atoms are arranged as two diamagnetic [4Fe-4S]2+ centers. Upon reduction, these two centers exhibit distinct and unusual Mossbauer spectroscopic parameters. The centers were found to have similar mid-point potentials (approximately -315 mV) as determined by oxidation-reduction titratins followed by EPR.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy/methods; Hydrogenase/isolation & purification/*metabolism; Iron-Sulfur Proteins/isolation & purification/*metabolism; Macromolecular Substances; Metalloproteins/*metabolism; Nickel/analysis; Protein Conformation; Selenium/analysis; Spectrum Analysis/methods

Spin-equilibrium and heme-ligand alteration in a high-potential monoheme cytochrome (cytochrome c554) from Achromobacter cycloclastes, a denitrifying organism - Saraiva, L. M.; Liu, M. Y.; Payne, W. J.; Legall, J.; Moura, J. J.; Moura, I. (Eur J Biochem, 1990)
A c-type monoheme cytochrome c554 (13 kDa) was isolated from cells of Achromobacter cycloclastes IAM 1013 grown anaerobically as a denitrifier. The visible absorption spectrum indicates the presence of a band at 695 nm characteristic of heme-methionine coordination (low-spin form) coexisting with a minor high-spin form as revealed by the contribution at 630 nm. Magnetic susceptibility measurements support the existence of a small contribution of a high-spin form at all pH values, attaining a minimum at intermediate pH values. The mid-point redox potential determined by visible spectroscopy at pH 7.2 is +150 mV. The pH-dependent spin equilibrum and other relevant structural features were studied by 300-MHz 1H-NMR spectroscopy. In the oxidized form, the 1H-NMR spectrum shows pH dependence with pKa values at 5.0 and 8.9. According to these pKa values, three forms designated as I, II and III can be attributed to cytochrome c554. Forms I and II predominate at low pH values, and the 1H-NMR spectra reveal heme methyl proton resonances between 40 ppm and 22 ppm. These forms have a methionyl residue as a sixth ligand, and C6 methyl group of the bound methionine was identified in the low-field region of the NMR spectra. Above pH 9.6, form III predominates and the 1H-NMR spectrum is characterized by down-field hyperfine-shifted heme methyl proton resonances between 29 ppm and 22 ppm. Two new resonances are observed at congruent to 66 ppm and 54 ppm, and are taken as indicative of a new type of heme coordination (probably a lysine residue). These pH-dependent features of the 1H-NMR spectra are discussed in terms of the heme environment structure. The chemical shifts of the methyl resonances at different pH values exhibit anti-Curie temperature dependence. In the ferrous state, the 1H-NMR spectrum shows a methyl proton resonance at -3.9 ppm characteristic of methionine axial ligation. The electron-transfer rate between ferric and ferrous forms has been estimated to be smaller than 2 x 10(4) M-1 s-1 at pH 5. EPR spectroscopy was also used to probe the ferric heme environment. A prominent signal at gmax congruent to 3.58 and the overall lineshape of the spectrum indicate an almost axial heme environment.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Alcaligenes/*metabolism; Chromatography; Chromatography, DEAE-Cellulose; Chromatography, Gel; Chromatography, High Pressure Liquid; Cytochrome c Group/isolation & purification/*metabolism; Durapatite; Heme/*metabolism; Hydrogen-Ion Concentration; Hydroxyapatites; Kinetics; Ligands; Oxidation-Reduction; Spectrophotometry; Thermodynamics

The enthalpy and entropy of cavity formation in liquids and corresponding states principle - M. Dionísio; J. J. Moura Ramos; R. M. Gonçalves (Canadian Journal of Chemistry, 1990)

The n-alkane solvent effect on the dipole moment of the trans-1,2-dibromocyclohexane - M. Dionísio; L. N. Almeida; J. Moura Ramos (Bulletin des Sociétés Chimiques Belges, 1990)

Programmable Cardiac Simulator - A.G., B (2nd Portuguese Congress of Biomedical Engineering, 1990)
n/a

Programmable Cardiac Simulator - Batista, A.G. (1990)
n/a

FLUORESCENCE-SPECTRA AND DECAYS OF MALVIDIN 3,5-DIGLUCOSIDE IN AQUEOUS-SOLUTIONS - FIGUEIREDO, P; Pina, F; Vilasboas, L.; Macanita, AL (Journal of Photochemistry and Photobiology a-Chemistry, 1990)
n/a
Times Cited: 15 Figueiredo, Paulo/A-2078-2012; Figueiredo, Paulo/A-2429-2012; Figueiredo, Paulo/A-2425-2012; Pina, Fernando/C-8161-2011; Macanita, Antonio/H-9284-2012; Vilas Boas, Luis/I-5634-2012; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Figueiredo, Paulo/0000-0002-8340-9316; Pina, Fernando/0000-0001-8529-6848; Macanita, Antonio/0000-0003-0976-6654; 15

Metal ion binding of copper(II), zinc(II) and lead(II) to cytochrome C - Simões Gonçalves, M. L. S.; Lopes da Conceição, A. C.; Moura, J. J. G. (Electrochimica Acta, 1990)
n/a
n/a

PHOTOCHEMISTRY OF THE CO(SEP)3+-I- SYSTEM - EVALUATION OF THE QUANTUM YIELD FOR THE PHOTOCHEMICAL REDOX REACTION OF THE ION-PAIR - Pina, F; J. Sotomayor; Moggi, L. (Journal of Photochemistry and Photobiology a-Chemistry, 1990)
n/a
Times Cited: 6 Pina, Fernando/C-8161-2011; Sotomayor, Joao/D-8103-2013; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; Sotomayor, Joao/0000-0002-4589-0591; 6

Programmable Cardiac Simulator - Batista A.G. (2nd Portuguese Congress of Biomedical Engineering, 1990)
n/a
n/a

Programmable Cardiac Simulator - Batista, A.G. (2nd Portuguese Congress of Biomedical Engineering, 1990)
n/a
n/a

PURIFICATION AND CHARACTERIZATION OF DESULFOFERRODOXIN - A NOVEL PROTEIN FROM DESULFOVIBRIO-DESULFURICANS (ATCC-27774) AND FROM DESULFOVIBRIO-VULGARIS (STRAIN HILDENBOROUGH) THAT CONTAINS A DISTORTED RUBREDOXIN CENTER AND A MONONUCLEAR FERROUS CENTER - Moura, I.; Tavares, P; Moura, J. J. G.; Ravi, N.; Huynh, B. H.; Liu, M. Y.; Legall, J. (Journal Of Biological Chemistry, 1990)
n/a
n/a

MODERNIZAÇÃO DA INDÚSTRIA PORTUGUESA: Análise de um inquérito sociológico [Modernization of Portuguese Industry: Analysis of a sociological survey] - António Moniz (University Library of Munich, Germany, 1989)
The analysis on the technological and organizational change in the European industry, and particularlly the Portuguese one, has been studied at CESO I&D since its foundation on 1988. Few time after that, started a development project that started from a previous research project on the same topics, and supported by JNICT (Ministry of Science). In that projecto we continued to process data that was then not possible to do in the first one. It was then possible to continue a research programme that was urgent and determinant in the field of industrial sociology in Portugal. It focus again on the processes of technological and organizational change in the manufacturing industry.
n/a
Keywords: manufacturing industry; organizational change; Portugal; sociology; survey; technology

{MODERNIZAÇÃO DA INDÚSTRIA PORTUGUESA: Análise de um inquérito sociológico [Modernization of Portuguese Industry: Analysis of a sociological survey]} - António Moniz (University Library of Munich, Germany, 1989)
The analysis on the technological and organizational change in the European industry, and particularlly the Portuguese one, has been studied at CESO I&D since its foundation on 1988. Few time after that, started a development project that started from a previous research project on the same topics, and supported by JNICT (Ministry of Science). In that projecto we continued to process data that was then not possible to do in the first one. It was then possible to continue a research programme that was urgent and determinant in the field of industrial sociology in Portugal. It focus again on the processes of technological and organizational change in the manufacturing industry.
n/a
Keywords: manufacturing industry; organizational change; Portugal; sociology; survey; technology

Redox intermediates of Desulfovibrio gigas [NiFe] hydrogenase generated under hydrogen. Mossbauer and EPR characterization of the metal centers - Teixeira, M.; Moura, I.; Xavier, A. V.; Moura, J. J.; Legall, J.; Dervartanian, D. V.; Peck, H. D., Jr.; Huynh, B. H. (J Biol Chem, 1989)
The hydrogenase (EC 1.2.2.1) of Desulfovibrio gigas is a complex enzyme containing one nickel center, one [3Fe-4S] and two [4Fe-4S] clusters. Redox intermediates of this enzyme were generated under hydrogen (the natural substrate) using a redox-titration technique and were studied by EPR and Mossbauer spectroscopy. In the oxidized states, the two [4Fe-4S]2+ clusters exhibit a broad quadrupole doublet with parameters (apparent delta EQ = 1.10 mm/s and delta = 0.35 mm/s) typical for this type of cluster. Upon reduction, the two [4Fe-4S]1+ clusters are spectroscopically distinguishable, allowing the determination of their midpoint redox potentials. The cluster with higher midpoint potential (-290 +/- 20 mV) was labeled Fe-S center I and the other with lower potential (-340 +/- 20 mV), Fe-S center II. Both reduced clusters show atypical magnetic hyperfine coupling constants, suggesting structural differences from the clusters of bacterial ferredoxins. Also, an unusually broad EPR signal, labeled Fe-S signal B', extending from approximately 150 to approximately 450 mT was observed concomitantly with the reduction of the [4Fe-4S] clusters. The following two EPR signals observed at the weak-field region were tentatively attributed to the reduced [3Fe-4S] cluster: (i) a signal with crossover point at g approximately 12, labeled the g = 12 signal, and (ii) a broad signal at the very weak-field region (approximately 3 mT), labeled the Fe-S signal B. The midpoint redox potential associated with the appearance of the g = 12 signal was determined to be -70 +/- 10 mV. At potentials below -250 mV, the g = 12 signal began to decrease in intensity, and simultaneously, the Fe-S signal B appeared. The transformation of the g = 12 signal into the Fe-S signal B was found to parallel the reduction of the two [4Fe-4S] clusters indicating that the [3Fe-4S]o cluster is sensitive to the redox state of the [4Fe-4S] clusters. Detailed redox profiles for the previously reported Ni-signal C and the g = 2.21 signal were obtained in this study, and evidence was found to indicate that these two signals represent two different oxidation states of the enzyme. Finally, the mechanistic implications of our results are discussed.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogenase/*metabolism; Iron-Sulfur Proteins/metabolism; Iron/analysis; Kinetics; Nickel/analysis; Oxidation-Reduction; Spectrum Analysis

Electron transport in sulfate-reducing bacteria. Molecular modeling and NMR studies of the rubredoxin--tetraheme-cytochrome-c3 complex - Stewart, D. E.; Legall, J.; Moura, I.; Moura, J. J.; Peck, H. D., Jr.; Xavier, A. V.; Weiner, P. K.; Wampler, J. E. (Eur J Biochem, 1989)
A hypothetical model of the complex formed between the iron-sulfur protein rubredoxin and the tetraheme cytochrome c3 from the sulfate-reducing bacteria Desulfovibrio vulgaris (Hildenborough) has been proposed utilizing computer graphic modeling, computational methods and NMR spectroscopy. The proposed complex appears feasible on the basis of complementary electrostatic interaction and steric factors and is consistent with the data from NMR experiments. In this model, the non-heme iron atom of rubredoxin is in close proximity to heme 1 of cytochrome c3. The complex is stabilized by charge-pair interactions and hydrogen bonds. This complex is compared to the flavodoxin-cytochrome c3 complex previously proposed [Stewart, D. E., LeGall, J., Moura, I., Moura, J. J. G., Peck, H. D. Jr, Xavier, A. V., Weiner, P. K. & Wampler, J. E. (1988) Biochemistry 27, 2444-2450] and new NMR data shows that both proteins interact with the same heme group of the cytochrome as postulated.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Binding Sites; Computer Graphics; Cytochrome c Group/*metabolism; Desulfovibrio/enzymology/*metabolism; Electron Transport; Energy Transfer; Ferredoxins/*metabolism; Flavodoxin/analysis; Magnetic Resonance Spectroscopy; Models, Molecular; Oxidation-Reduction; Rubredoxins/*metabolism; Sulfates/*metabolism

The Role Of Nickel And Iron Sulfur Centers In The Bioproduction Of Hydrogen - Moura, J. J. G.; Teixeira, M.; Moura, I. (Pure and Applied Chemistry, 1989)
n/a
Times Cited: 27

Redox properties of the diheme cytochrome c4 from Azotobacter vinelandii and characterisation of the two hemes by NMR, MCD and EPR spectroscopy - Gadsby, P. M.; Hartshorn, R. T.; Moura, J. J.; Sinclair-Day, J. D.; Sykes, A. G.; Thomson, A. J. (Biochim Biophys Acta, 1989)
From biphasic stopped-flow kinetic studies it has been established that the two heme centres of cytochrome c4 from Azotobacter vinelandii undergo redox change with [Co(terpy)2]3+/2+ (260 mV) at different rates. Rate constants for oxidation and reduction at pH 7.5 give reduction potentials for the two heme centres in agreement with previous values from spectrophotometric titrations (263 and 317 mV). From NMR studies on the fully reduced protein two sharp methyl methionine resonances are observed at -3.16 and -3.60 ppm, consistent with axial methionine coordination. On titration with [Fe(CN)6]3- the -3.16 ppm resonance is the first to disappear, and is assigned to the less positive reduction potential. Line-broadening effects are observed on partial oxidation, which are dominated by intermolecular processes in an intermediate time-range exchange process. The hemes of the oxidised protein are distinguishable by EPR g-values of 3.64 and 3.22. The former is of interest because it is at an unusually low field for histidine/methionine coordination, and has an asymmetric or ramp shape. The latter assigned to the low potential heme is similar to that of a cytochrome c551. The MCD spectra of the fully oxidised protein are typical of low-spin Fe(III) heme centres, with a negative peak at 710 nm characteristic of methionine coordination, and an NIR peak at 1900 nm characteristic of histidine/methionine (axial) coordination. Of the four histidines per molecule only two undergo diethyl pyrocarbonate (DEPC) modification.
0006-3002 (Print)0006-3002 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: *Cytochrome c Group; *Heme; Azotobacter/*analysis; Diethyl Pyrocarbonate; Electron Spin Resonance Spectroscopy; Histidine; Hydrogen-Ion Concentration; Kinetics; Magnetic Resonance Spectroscopy; Methionine; Oxidation-Reduction; Spectrophotometry; Spectrum Analysis

Evidence for selenocysteine coordination to the active site nickel in the [NiFeSe]hydrogenases from Desulfovibrio baculatus - Eidsness, M. K.; Scott, R. A.; Prickril, B. C.; Dervartanian, D. V.; Legall, J.; Moura, I.; Moura, J. J.; Peck, H. D., Jr. (Proc Natl Acad Sci U S A, 1989)
Ni and Se x-ray absorption spectroscopic studies of the [NiFeSe]hydrogenases from Desulfovibrio baculatus are described. The Ni site geometry is pseudo-octahedral with a coordinating ligand composition of 3-4 (N,O) at 2.06 A, 1-2 (S,Cl) at 2.17 A, and 1 Se at 2.44 A. The Se coordination environment consists of 1 C at 2.0 A and a heavy scatterer M (M = Ni or Fe) at approximately 2.4 A. These results are interpreted in terms of a selenocysteine residue coordinated to the Ni site. The possible role of the Ni-Se site in the catalytic activation of H2 is discussed.
0027-8424 (Print)0027-8424 (Linking)Journal ArticleResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: *Nickel; *Selenium/metabolism; Binding Sites; Cysteine/*analogs & derivatives; Desulfovibrio/*enzymology; Hydrogenase/*metabolism; Iron/metabolism; Metalloendopeptidases/*metabolism; Oxidation-Reduction; Protein Conformation; Selenocysteine; Spectrum Analysis

EPR studies with 77Se-enriched (NiFeSe) hydrogenase of Desulfovibrio baculatus. Evidence for a selenium ligand to the active site nickel - He, S. H.; Teixeira, M.; Legall, J.; Patil, D. S.; Moura, I.; Moura, J. J.; Dervartanian, D. V.; Huynh, B. H.; Peck, H. D., Jr. (J Biol Chem, 1989)
The periplasmic hydrogenase containing equivalent amounts of nickel and selenium plus non-heme iron [NiFeSe) hydrogenase) has been purified from cells of the sulfate reducing bacterium Desulfovibrio baculatus (DSM 1748) grown on a lactate/sulfate medium containing natural Se isotopes and the nuclear isotope, 77Se. Both the 77Se-enriched and unenriched hydrogenases were shown to be free of other hydrogenases and characterized with regard to their Se contents. EPR studies of the reduced nickel signal generated by redox titrations of the enriched and unenriched (NiFeSe) hydrogenases demonstrated that the gx = 2.23 and gy = 2.17 resonances are appreciably broadened by the spin of the 77Se nucleus (I = 1/2). This observation demonstrates unambiguously that the unpaired electron is shared by the Ni and Se atoms and that Se serves as a ligand to the nickel redox center of the (NiFeSe) hydrogenase.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Binding Sites; Chromatography, DEAE-Cellulose; Chromatography, Gel; Chromatography, High Pressure Liquid; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogenase/*isolation & purification/metabolism; Kinetics; Ligands; Nickel/*analysis; Selenium/*analysis

PHOTOCHEMISTRY OF SUPRAMOLECULAR SYSTEMS - SIZE AND CHARGE EFFECTS IN THE PHOTOAQUATION OF ADDUCTS OF THE HEXACYANOCOBALTATE(III) ANION WITH POLYAMMONIUM MACROCYCLIC RECEPTORS - Pina, F; Moggi, L.; Manfrin, M. F.; Balzani, V.; Hosseini, M. W.; Lehn, J. M. (Gazzetta Chimica Italiana, 1989)
n/a
Times Cited: 31 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 31

PHOTODECARBOXYLATION OF CITRATE THROUGH ION-PAIR PHOTOCHEMISTRY - THE CO(SEP)3+CITRATE1-, CITRATE2-, CITRATE3- SYSTEM - J. Sotomayor; Costa, J.C.; Mulazzani, Q. G.; Pina, F (Journal of Photochemistry and Photobiology a-Chemistry, 1989)
n/a
Times Cited: 7 Costa, Julia/B-7131-2008; Pina, Fernando/C-8161-2011; Sotomayor, Joao/D-8103-2013; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Costa, Julia/0000-0001-7782-6319; Pina, Fernando/0000-0001-8529-6848; Sotomayor, Joao/0000-0002-4589-0591; 7

QUANTUM YIELD DETERMINATIONS ON THE CO(EDTA) -I-SYSTEM - Pina, F; Costa, J.C. (Journal of Photochemistry and Photobiology a-Chemistry, 1989)
n/a
Times Cited: 6 Costa, Julia/B-7131-2008; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Costa, Julia/0000-0001-7782-6319; Pina, Fernando/0000-0001-8529-6848; 6

Assignment of individual heme EPR signals of Desulfovibrio baculatus (strain 9974) tetraheme cytochrome c3. A redox equilibria study - Moura, I.; Teixeira, M.; Huynh, B. H.; Legall, J.; Moura, J. J. (Eur J Biochem, 1988)
An EPR redox titration was performed on the tetraheme cytochrome c3 isolated from Desulfovibrio baculatus (strain 9974), a sulfate-reducer. Using spectral differences at different poised redox states of the protein, it was possible to individualize the EPR g-values of each of the four hemes and also to determine the mid-point redox potentials of each individual heme: heme 4 (-70 mV) at gmax = 2.93, gmed = 2.26 and gmin = 1.51; heme 3 (-280 mV) at gmax = 3.41; heme 2 (-300 mV) at gmax = 3.05, gmed = 2.24 and gmin = 1.34; and heme 1 (-355 mV) at gmx = 3.18. A previously described multi-redox equilibria model used for the interpretation of NMR data of D. gigas cytochrome c3 [Santos, H., Moura, J.J.G., Moura, I., LeGall, J. & Xavier, A. V. (1984) Eur. J. Biochem. 141, 283-296] is discussed in terms of the EPR results.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Cytochrome c Group/*metabolism; Desulfovibrio/*metabolism; Electron Spin Resonance Spectroscopy; Heme/*metabolism; Oxidation-Reduction

Chromosome aberrations in cattle raised on bracken fern pasture - Moura, J. W.; Stocco dos Santos, R. C.; Dagli, M. L.; D'Angelino, J. L.; Birgel, E. H.; Becak, W. (Experientia, 1988)
Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.
0014-4754 (Print)0014-4754 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: *Chromosome Aberrations; Animal Feed/*adverse effects; Animals; Bovine papillomavirus 1; Cattle; Cattle Diseases/*etiology/pathology; Plant Poisoning/pathology/*veterinary; Urinary Bladder Neoplasms/veterinary

Spectroscopic characterization of a high-potential monohaem cytochrome from Wolinella succinogenes, a nitrate-respiring organism. Redox and spin equilibria studies - Moura, I.; Liu, M. Y.; Costa, C.; Liu, M. C.; Pai, G.; Xavier, A. V.; Legall, J.; Payne, W. J.; Moura, J. J. (Eur J Biochem, 1988)
When purified, a high-potential c-type monohaem cytochrome from the nitrate-respiring organism, Wollinella succinogenes (VPI 10659), displayed a minimum molecular mass of 8.2 kDa and 0.9 mol iron and 0.95 mol haem groups/mol protein. Visible light spectroscopy suggested the presence of an equilibrium between two ligand arrangements around the haem, i.e. an absorption band at 695 nm characteristic of haem-methionine coordination (low-spin form) coexisting with a high-spin form revealed by a band at 619 nm and a shoulder at 498 nm. The mid-point redox potential measured by visible redox titration of the low-spin form was approximately +100 mV. Binding cyanide (Ka = 5 x 10(5) M-1) resulted in the displacement of the methionyl axial residue, and full conversion to a low-spin, cyanide-bound form. Structural features were studied by 300-MHz 1H-NMR spectroscopy. In the oxidized state, the pH dependence of the haem methyl resonances (pH range 5-10) and the magnetic susceptibility measurements (using an NMR method) were consistent with the visible light spectroscopic data for the presence of a high-spin/low-spin equilibrium with a transition pKa of 7.3. The spin equilibrium was fast on the NMR time scale. The haem methyl resonances presented large downfield chemical shifts. An unusually broad methyl resonance at around 35 ppm (pH = 7.5, 25 degrees C) was extremely temperature-dependent [delta(323 K) - delta(273 K) = 7.2 ppm] and was assigned to the S-CH3 group of the axial methionine. In the ferrous state only a low-spin form is present. The haem meso protons, the methyl group and the methylene protons from the axial methionine were identified in the reduced form. The resonances from the aromatic residues (three tyrosines and one phenylalanine) were also assigned. Detailed monitoring of the NMR-redox pattern of the monohaem cytochrome from the fully reduced up to the fully oxidized state revealed that the rate of the intermolecular electronic exchange process was approximately 6 x 10(6) M-1 s-1 at 303 K and pH = 6.31. A dihaem cytochrome also present in the crude cell extract and purified to a homogeneous state, exhibited a molecular mass of 11 kDa and contained 2.43 mol iron and 1.89 mol haem c moieties/mol cytochrome. The absorption spectrum in the visible region exhibited no band at 695 nm, suggesting that methione is not a ligand for either of the two haems. Recovery of only small amounts of this protein prevented more detailed structural analyzes.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Bacteroidaceae/*metabolism; Cytochromes/isolation & purification/*metabolism; Electron Spin Resonance Spectroscopy; Magnetic Resonance Spectroscopy; Nitrates/*metabolism; Oxidation-Reduction; Potassium Cyanide/metabolism

Isolation and characterization of rubrerythrin, a non-heme iron protein from Desulfovibrio vulgaris that contains rubredoxin centers and a hemerythrin-like binuclear iron cluster - Legall, J.; Prickril, B. C.; Moura, I.; Xavier, A. V.; Moura, J. J.; Huynh, B. H. (Biochemistry, 1988)
A new non-heme iron protein from the periplasmic fraction of Desulfovibrio vulgaris (Hildenbourough NCIB 8303) has been purified to homogeneity, and its amino acid composition, molecular weight, redox potential, iron content, and optical, EPR, and Mossbauer spectroscopic properties have been determined. This new protein is composed of two identical subunits with subunit molecular weight of 21,900 and contains four iron atoms per molecule. The as-purified oxidized protein exhibits an optical spectrum with absorption maxima at 492, 365, and 280 nm, and its EPR spectrum shows resonances at g = 4.3 and 9.4, characteristic of oxidized rubredoxin. The Mossbauer data indicate the presence of approximately equal amounts of two types of iron; we named them the Rd-like and the Hr-like iron due to their similarity to the iron centers of rubredoxins (Rds) and hemerythrins (Hrs), respectively. For the Rd-like iron, the measured fine and hyperfine parameters (D = 1.5 cm-1, E/D = 0.26, delta EQ = -0.55 mm/s, delta = 0.27 mm/s, Axx/gn beta n = -16.5 T, Ayy/gn beta n = -15.6 T, and Azz/gn beta n = -17.0 T) are almost identical with those obtained for the rubredoxin from Clostridium pasteurianum. Redox-titration studies monitored by EPR, however, showed that these Rd-like centers have a midpoint redox potential of +230 +/- 10 mV, approximately 250 mV more positive than those reported for rubredoxins. Another unusual feature of this protein is the presence of the Hr-like iron atoms.(ABSTRACT TRUNCATED AT 250 WORDS)
0006-2960 (Print)0006-2960 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Bacterial Proteins/*isolation & purification/metabolism; Desulfovibrio/growth & development/*metabolism; Electron Spin Resonance Spectroscopy; Ferredoxins/*isolation & purification/metabolism; Hemerythrin/metabolism; Iron/analysis; Kinetics; Molecular Weight; Oxidation-Reduction; Rubredoxins/metabolism; Spectrophotometry; Spectrum Analysis

Magnetization of the oxidized and reduced three-iron cluster of Desulfovibrio gigas ferredoxin II - Day, E. P.; Peterson, J.; Bonvoisin, J. J.; Moura, I.; Moura, J. J. (J Biol Chem, 1988)
The saturation magnetizations of the three iron cluster of ferredoxin II of Desulfovibrio gigas in both the oxidized and reduced states have been studied at fixed magnetic fields up to 4.5 tesla over the temperature range from 1.8 to 200 K. The low field (0.3 tesla) susceptibility of oxidized ferredoxin II obeys the Curie law over this entire temperature range. This establishes -2Jox greater than 200 cm-1 as the lower limit for the antiferromagnetic exchange coupling of oxidized ferredoxin II. The saturation magnetizations of reduced ferredoxin II at several fixed fields yield a nested family of curves which can be fit with spin S = 2 and D = -2.7(4) cm-1 (with E/D assigned the value 0.23 as determined by Mossbauer and EPR spectra). The low field susceptibility of reduced ferredoxin II also obeys the Curie law from approximately 4 up to 200 K. This establishes -2Jred greater than 40 cm-1 as the lower limit for the antiferromagnetic coupling of reduced ferredoxin II.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, U.S. Gov't, P.H.S.
Keywords: Desulfovibrio/*metabolism; Electron Spin Resonance Spectroscopy; Ferredoxins/*metabolism; Iron/*metabolism; Kinetics; Magnetics; Oxidation-Reduction; Spectrum Analysis

EPR-detectable redox centers of the periplasmic hydrogenase from Desulfovibrio vulgaris - Patil, D. S.; Moura, J. J.; He, S. H.; Teixeira, M.; Prickril, B. C.; Dervartanian, D. V.; Peck, H. D., Jr.; Legall, J.; Huynh, B. H. (J Biol Chem, 1988)
The periplasmic hydrogenase of Desulfovibrio vulgaris (Hildenbourough NCIB 8303) belongs to the category of [Fe] hydrogenase which contains only iron-sulfur clusters as its prosthetic groups. Amino acid analyses were performed on the purified D. vulgaris hydrogenase. The amino acid composition obtained compared very well with the result derived from the nucleotide sequence of the structural gene (Voordouw, G., Brenner, S. (1985) Eur. J. Biochem. 148, 515-520). Detailed EPR reductive titration studies on the D. vulgaris hydrogenase were performed to characterize the metal centers in this hydrogenase. In addition to the three previously observed EPR signals (namely, the "isotropic" 2.02 signal, the rhombic 2.10 signal, and the complex signal of the reduced enzyme), a rhombic signal with resonances at the g-values of 2.06, 1.96, and 1.89 (the rhombic 2.06 signal) was detected when the samples were poised at potentials between 0 and -250 mV (with respect to normal hydrogen electrode). The midpoint redox potentials for each of the four EPR-active species were determined, and the characteristics of each EPR signal are described. Both the rhombic 2.10 and 2.06 signals exhibit spectral properties that are distinct from a ferredoxin-type [4Fe-4S] cluster and are proposed to originate from the same H2-binding center but in two different conformations. The complex signal of the reduced hydrogenase has been shown to represent two spin-spin interacting ferredoxin-type [4Fe-4S]1+ clusters (Grande, H. J., Dunham, W. R., Averill, B., Van Dijk, C., and Sands, R. H. (1983) Eur. J. Biochem. 136, 201-207). The titration data indicated a strong cooperative effect between these two clusters during their reduction. In an effort to accurately estimate the number of iron atoms/molecule of hydrogenase, plasma emission and chemical methods were used to determine the iron contents in the samples; and four different methods, including amino acid analysis, were used for protein determination. The resulting iron stoichiometries were found to be method-dependent and vary over a wide range (+/- 20%). The uncertainties involved in the determination of iron stoichiometry are discussed.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: *Hydrogenase; Amino Acids/analysis; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Iron/analysis; Oxidation-Reduction

Cytochrome components of nitrate- and sulfate-respiring Desulfovibrio desulfuricans ATCC 27774 - Liu, M. C.; Costa, C.; Coutinho, I. B.; Moura, J. J.; Moura, I.; Xavier, A. V.; Legall, J. (J Bacteriol, 1988)
Three multiheme c-type cytochromes--the tetraheme cytochrome c3 (molecular weight [MW] 13,500), a dodecaheme cytochrome c (MW 40,800), and a "split-Soret" cytochrome c (MW 51,540), which is a dimer with 2 hemes per subunit (MW 26,300)--were isolated from the soluble fraction of Desulfovibrio desulfuricans (ATCC 27774) grown under nitrate- or sulfate-respiring conditions. Two of them, the dodecaheme and the split-Soret cytochromes, showed no similarities to any of the c-type cytochromes isolated from other sulfate-reducing bacteria, while the tetraheme cytochrome c3 appeared to be analogous to the cytochrome c3 found in other sulfate-reducing bacteria. For all three multiheme c-type cytochromes isolated, the homologous proteins from nitrate- and sulfate-grown cells were indistinguishable in amino acid composition, physical properties, and spectroscopic characteristics. It therefore appears that the same c-type cytochrome components are present when D. desulfuricans ATCC 27774 cells are grown under either condition. This is in contrast to the considerable difference found in Pseudomonas perfectomarina (Liu et al., J. Bacteriol. 154:278-286, 1983), a marine denitrifier, when the cells are grown on nitrate or oxygen as the terminal electron acceptor. In addition, two spectroscopy methods capable of revealing minute structural variations in proteins provided identical information about the tetraheme cytochrome c3 from nitrate-grown and sulfate-grown cells.
0021-9193 (Print)0021-9193 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Amino Acids/analysis; Cytochrome c Group/*isolation & purification/metabolism; Desulfovibrio/growth & development/*metabolism; Electron Spin Resonance Spectroscopy; Magnetic Resonance Spectroscopy; Molecular Weight; Nitrates/*metabolism; Oxygen Consumption; Spectrophotometry; Sulfates/*metabolism

Hydrogen production and deuterium-proton exchange reactions catalyzed by Desulfovibrio nickel(II)-substituted rubredoxins - Saint-Martin, P.; Lespinat, P. A.; Fauque, G.; Berlier, Y.; Legall, J.; Moura, I.; Teixeira, M.; Xavier, A. V.; Moura, J. J. (Proc Natl Acad Sci U S A, 1988)
The nickel tetrahedral sulfur-coordinated core formed upon metal replacement of the native iron in Desulfovibrio sp. rubredoxins is shown to mimic the reactivity pattern of nickel-containing hydrogenases with respect to hydrogen production, deuterium-proton exchange, and inhibition by carbon monoxide.
0027-8424 (Print)0027-8424 (Linking)Journal Article

The three classes of hydrogenases from sulfate-reducing bacteria of the genus Desulfovibrio - Fauque, G.; Peck, H. D., Jr.; Moura, J. J.; Huynh, B. H.; Berlier, Y.; Dervartanian, D. V.; Teixeira, M.; Przybyla, A. E.; Lespinat, P. A.; Moura, I.; ,; et al (FEMS Microbiol Rev, 1988)
Three types of hydrogenases have been isolated from the sulfate-reducing bacteria of the genus Desulfovibrio. They differ in their subunit and metal compositions, physico-chemical characteristics, amino acid sequences, immunological reactivities, gene structures and their catalytic properties. Broadly, the hydrogenases can be considered as 'iron only' hydrogenases and nickel-containing hydrogenases. The iron-sulfur-containing hydrogenase ([Fe] hydrogenase) contains two ferredoxin-type (4Fe-4S) clusters and an atypical iron-sulfur center believed to be involved in the activation of H2. The [Fe] hydrogenase has the highest specific activity in the evolution and consumption of hydrogen and in the proton-deuterium exchange reaction and this enzyme is the most sensitive to CO and NO2-. It is not present in all species of Desulfovibrio. The nickel-(iron-sulfur)-containing hydrogenases [( NiFe] hydrogenases) possess two (4Fe-4S) centers and one (3Fe-xS) cluster in addition to nickel and have been found in all species of Desulfovibrio so far investigated. The redox active nickel is ligated by at least two cysteinyl thiolate residues and the [NiFe] hydrogenases are particularly resistant to inhibitors such as CO and NO2-. The genes encoding the large and small subunits of a periplasmic and a membrane-bound species of the [NiFe] hydrogenase have been cloned in Escherichia (E.) coli and sequenced. Their derived amino acid sequences exhibit a high degree of homology (70%); however, they show no obvious metal-binding sites or homology with the derived amino acid sequence of the [Fe] hydrogenase. The third class is represented by the nickel-(iron-sulfur)-selenium-containing hydrogenases [( NiFe-Se] hydrogenases) which contain nickel and selenium in equimolecular amounts plus (4Fe-4S) centers and are only found in some species of Desulfovibrio. The genes encoding the large and small subunits of the periplasmic hydrogenase from Desulfovibrio (D.) baculatus (DSM 1743) have been cloned in E. coli and sequenced. The derived amino acid sequence exhibits homology (40%) with the sequence of the [NiFe] hydrogenase and the carboxy-terminus of the gene for the large subunit contains a codon (TGA) for selenocysteine in a position homologous to a codon (TGC) for cysteine in the large subunit of the [NiFe] hydrogenase. EXAFS and EPR studies with the 77Se-enriched D. baculatus hydrogenase indicate that selenium is a ligand to nickel and suggest that the redox active nickel is ligated by at least two cysteinyl thiolate and one selenocysteine selenolate residues.(ABSTRACT TRUNCATED AT 400 WORDS)
0168-6445 (Print)0168-6445 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.Review
Keywords: Amino Acid Sequence; Desulfovibrio/*enzymology/genetics; Hydrogenase/*analysis/genetics/physiology; Molecular Sequence Data

A hypothetical model of the flavodoxin-tetraheme cytochrome c3 complex of sulfate-reducing bacteria - Stewart, D. E.; Legall, J.; Moura, I.; Moura, J. J.; Peck, H. D., Jr.; Xavier, A. V.; Weiner, P. K.; Wampler, J. E. (Biochemistry, 1988)
A hypothetical model of the flavodoxin-tetraheme cytochrome c3 electron-transfer complex from the sulfate-reducing bacterium Desulfovibrio vulgaris has been constructed by using interactive computer graphics based on electrostatic potential field calculations and previous NMR experiments. Features of the proposed complex are (1) van der Waals contact between the flavin mononucleotide prosthetic group of flavodoxin and one heme of the cytochrome, (2) unique complementarity of electrostatic fields between the region surrounding this heme and the region surrounding the exposed portion of the flavin mononucleotide group of flavodoxin, and (3) no steric interferences between the two polypeptide chains in the complex. This complex is consistent with all structural and spectroscopic data available.
0006-2960 (Print)0006-2960 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Cytochrome c Group/*metabolism; Desulfovibrio/*metabolism; Flavin Mononucleotide/metabolism; Flavodoxin/*metabolism; Flavoproteins/*metabolism; Heme/metabolism; Kinetics; Models, Molecular; Protein Conformation

Electronic and magnetic properties of nickel-substituted rubredoxin: a variable-temperature magnetic circular dichroism study - Kowal, Andrzej T.; Zambrano, Isabel C.; Moura, Isabel; Moura, Jose J. G.; Legall, Jean; Johnson, Michael K. (Inorganic Chemistry, 1988)
n/a
doi: 10.1021/ic00280a015

Characterization of two dissimilatory sulfite reductases (desulforubidin and desulfoviridin) from the sulfate-reducing bacteria. Moessbauer and EPR studies - Moura, I.; Legall, J.; Lino, A. R.; Peck, H. D.; Fauque, G.; Xavier, A. V.; Dervartanian, D. V.; Moura, J. J. G.; Huynh, B. H. (Journal of the American Chemical Society, 1988)
n/a
doi: 10.1021/ja00212a013

Characterization of two dissimilatory sulfite reductases from sulfate-reducing bacteria - Huynh, B. H.; Moura, I.; Lino, A. R.; Moura, J. J. G.; Legall, J. (Hyperfine Interactions, 1988)
n/a
Times Cited: 0

NICKEL-CONTAINING HYDROGENASES - Moura, J. J. G.; Moura, I.; Teixeira, M.; Xavier, A. V.; Fauque, G. D.; Legall, J. (Metal Ions in Biological Systems, 1988)
n/a
Times Cited: 23

A further view on the calculation of the enthalpy of cavity formation in liquids. The influence of the cavity size and shape - J. J. Moura Ramos; M. Dionísio; R. Gonçalves; H. Diogo (Canadian Journal of Chemistry, 1988)

Characterization of two dissimilatory sulfite reductases from sulfate-reducing bacteria - Huynh, B.; Moura, I.; Lino, A.; Moura, J.; Legall, J. (Hyperfine Interactions, 1988)
Mössbauer, EPR, and biochemical techniques were used to characterize two dissimilatory sulfite reductases: desulforubidin from Desulfovibrio baculatus strain DSM 1743 and desulfoviridin from Desulfovibrio gigas . For each molecule of desulforubidin, there are two sirohemes and four [4Fe−4S] clusters. The [4Fe−4S] clusters are in the diamagnetic 2+ oxidation state. The sirohemes are high-spin ferric (S=5/2) and each siroheme is exchanged-coupled to a [4Fe−4S] 2+ cluster. Such an exchange-coupled siroheme-[4Fe−4S] unit has also been found in the assimilatory sulfite reductase from Escherichia coli /1/ and in a low-molecular weight sulfite reductase from Desulfovibrio vulgaris /2/. For each molecule of defulfoviridin, there are two tetrahydroporphyrin groups and four [4Fe−4S] 2+ clusters. To our surprise, we discovered that about 80% of the tetrahydroporphyrin groups, however, do not bind iron.
n/a
Keywords: Physics and Astronomy

Immunocytochemical localization of APS reductase and bisulfite reductase in three Desulfovibrio species - Kremer, D. R.; Veenhuis, M.; Fauque, G.; Peck, H. D.; Legall, J.; Lampreia, J.; Moura, J. J. G.; Hansen, T. A. (Archives of Microbiology, 1988)
The localization of APS reductase and bisulfite reductase in Desulfovibrio gigas, D. vulgaris Hildenborough and D. thermophilus was studied by immunoelectron microscopy. Polyclonal antibodies were raised against the purified enzymes from each strain. Cells fixed with formaldehyde/glutaraldehyde were embedded and ultrathin sections were incubated with antibodies and subsequently labeled with protein A-gold. The bisulfite reductase in all three strains and APS reductase in d. gigas and D. vulgaris were found in the cytoplasm. The labeling of d. thermophilus with APS reductase antibodies resulted in a distribution of gold particles over the cytoplasmic membrane region. The localization of the two enzymes is discussed with respect to the mechanism and energetics of dissimilatory sulfate reduction.
n/a
Keywords: Biomedical and Life Sciences

A KINETIC-STUDY OF PHOTOSUBSTITUTION OF CARBON-MONOXIDE AND TRIPHENYLPHOSPHINE IN COMPLEXES MN(ETA-5-CH3C5H4)(CO)3-N(PPH3)N (N=0, 1 AND 2) - Teixeira, G.; Aviles, T.; Dias, A. R.; Pina, F (Journal of Organometallic Chemistry, 1988)
n/a
Times Cited: 13 Aviles, Teresa/G-4399-2011; Pina, Fernando/C-8161-2011; Aviles, Teresa/B-1464-2012; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 13

A PHOTOCATALYTIC CYCLE FOR MILD OXIDATION BY DIOXYGEN OF SUBSTRATES EASILY OXIDIZABLE BY IODINE - FIGUEIREDO, P; Pina, F (Journal of Photochemistry and Photobiology a-Chemistry, 1988)
n/a
Times Cited: 2 Figueiredo, Paulo/A-2078-2012; Figueiredo, Paulo/A-2429-2012; Figueiredo, Paulo/A-2425-2012; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Figueiredo, Paulo/0000-0002-8340-9316; Pina, Fernando/0000-0001-8529-6848; 2

PHOTOCHEMISTRY OF CO(EDTA)–I-SYSTEM IN AQUEOUS-SOLUTIONS - Pina, F; Maestri, M (Inorganica Chimica Acta, 1988)
n/a
Times Cited: 8 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 8

The molybdenum iron-sulphur protein from Desulfovibrio gigas as a form of aldehyde oxidase - Turner, N.; Barata, B.; Bray, R. C.; Deistung, J.; Legall, J.; Moura, J. J. (Biochem J, 1987)
The molybdenum iron-sulphur protein originally isolated from Desulfovibrio gigas by Moura, Xavier, Bruschi, Le Gall, Hall & Cammack [(1976) Biochem. Biophys. Res. Commun. 72, 782-789] has been further investigated by e.p.r. spectroscopy of molybdenum(V). The signal obtained on extended reduction of the protein with sodium dithionite has been shown, by studies at 9 and 35 HGz in 1H2O and 2H2O and computer simulations, to have parameters corresponding to those of the Slow signal from the inactive desulpho form of various molybdenum-containing hydroxylases. Another signal obtained on brief reduction of the protein with small amounts of dithionite was shown by e.p.r. difference techniques to be a Rapid type 2 signal, like that from the active form of such enzymes. In confirmation that the protein is a molybdenum-containing hydroxylase, activity measurements revealed that it had aldehyde:2,6-dichlorophenol-indophenol oxidoreductase activity. No such activity towards xanthine or purine was observed. Salicylaldehyde was a particularly good substrate, and treatment of the protein with it also gave rise to the Rapid signal. Molybdenum cofactor liberated from the protein was active in the nit-1 Neurospora crassa nitrate reductase assay. It is concluded that the protein is a form of an aldehyde oxidase or dehydrogenase. From the intensity of the e.p.r. signals and from enzyme activity measurements, 10-30% of the protein in the sample examined appeared to be in the functional form. The evolutionary significance of the protein, which may represent a primitive form of the enzyme rather than a degradation product, is discussed briefly.
0264-6021 (Print)0264-6021 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: *Aldehyde Oxidoreductases; Aldehyde Oxidase; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Molybdenum/analysis; Xanthine Oxidase

On the active sites of the [NiFe] hydrogenase from Desulfovibrio gigas. Mossbauer and redox-titration studies - Huynh, B. H.; Patil, D. S.; Moura, I.; Teixeira, M.; Moura, J. J.; Dervartanian, D. V.; Czechowski, M. H.; Prickril, B. C.; Peck, H. D., Jr.; Legall, J. (J Biol Chem, 1987)
The [NiFe] hydrogenase isolated from Desulfovibrio gigas was poised at different redox potentials and studied by Mossbauer spectroscopy. The data firmly establish that this hydrogenase contains four prosthetic groups: one nickel center, one [3Fe-xS], and two [4Fe-4S] clusters. In the native enzyme, both the nickel and the [3Fe-xS] cluster are EPR-active. At low temperature (4.2 K), the [3Fe-xS] cluster exhibits a paramagnetic Mossbauer spectrum typical for oxidized [3Fe-xS] clusters. At higher temperatures (greater than 20 K), the paramagnetic spectrum collapses into a quadrupole doublet with parameters magnitude of delta EQ magnitude of = 0.7 +/- 0.06 mm/s and delta = 0.36 +/- 0.06 mm/s, typical of high-spin Fe(III). The observed isomer shift is slightly larger than those observed for the three-iron clusters in D. gigas ferredoxin II (Huynh, B. H., Moura, J. J. G., Moura, I., Kent, T. A., LeGall, J., Xavier, A. V., and Munck, E. (1980) J. Biol. Chem. 255, 3242-3244) and in Azotobacter vinelandii ferredoxin I (Emptage, M. H., Kent, T. A., Huynh, B. H., Rawlings, J., Orme-Johnson, W. H., and Munck, E. (1980) J. Biol. Chem. 255, 1793-1796) and may indicate a different iron coordination environment. When D. gigas hydrogenase is poised at potentials lower than -80 mV (versus normal hydrogen electrode), the [3Fe-xS] cluster is reduced and becomes EPR-silent. The Mossbauer data indicate that the reduced [3Fe-xS] cluster remains intact, i.e. it does not interconvert into a [4Fe-4S] cluster. Also, the electronic properties of the reduced [3Fe-xS] cluster suggest that it is magnetically isolated from the other paramagnetic centers.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Binding Sites; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogenase/*metabolism; Oxidation-Reduction; Spectrum Analysis/methods

Characterization of the cytochrome system of a nitrogen-fixing strain of a sulfate-reducing bacterium: Desulfovibrio desulfuricans strain Berre-Eau - Moura, I.; Fauque, G.; Legall, J.; Xavier, A. V.; Moura, J. J. (Eur J Biochem, 1987)
Two c-type cytochromes were purified and characterized by electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopic techniques, from the sulfate-reducer nitrogen-fixing organism, Desulfovibrio desulfuricans strain Berre-Eau (NCIB 8387). The purification procedures included several chromatographic steps on alumina, carboxymethylcellulose and gel filtration. A tetrahaem and a monohaem cytochrome were identified. The multihaem cytochrome has visible, EPR and NMR spectra with general properties similar to other low-potential bis-histidinyl axially bound haem proteins, belonging to the class of tetrahaem cytochrome c3 isolated from other Desulfovibrio species. The monohaem cytochrome c553 is ascorbate-reducible and its EPR and NMR data are characteristic of a cytochrome with methionine-histidine ligation. Their properties are compared with other homologous proteins isolated from sulfate-reducing bacteria.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Cytochrome c Group/*analysis; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Heme/analysis; Magnetic Resonance Spectroscopy; Molecular Weight; Nitrogen Fixation; Oxidation-Reduction; Spectrophotometry; Sulfates/metabolism; Temperature

Characterization Of Electron-Transfer Proteins From The Nitrogen-Fixing Sulfate-Reducing Bacterium Desulfovibrio-Desulfuricans Berre-Eau - Fauque, G.; Moura, I.; Xavier, A. V.; Galliano, N.; Moura, J. J. G.; Legall, J. (Biochemical Society Transactions, 1987)
n/a
Times Cited: 0

Nickel-[iron-sulfur]-selenium-containing hydrogenases from Desulfovibrio baculatus (DSM 1743). Redox centers and catalytic properties - Teixeira, M.; Fauque, G.; Moura, I.; Lespinat, P. A.; Berlier, Y.; Prickril, B.; Peck, H. D., Jr.; Xavier, A. V.; Legall, J.; Moura, J. J. (Eur J Biochem, 1987)
The hydrogenase from Desulfovibrio baculatus (DSM 1743) was purified from each of three different fractions: soluble periplasmic (wash), soluble cytoplasmic (cell disruption) and membrane-bound (detergent solubilization). Plasma-emission metal analysis detected in all three fractions the presence of iron plus nickel and selenium in equimolecular amounts. These hydrogenases were shown to be composed of two non-identical subunits and were distinct with respect to their spectroscopic properties. The EPR spectra of the native (as isolated) enzymes showed very weak isotropic signals centered around g approximately 2.0 when observed at low temperature (below 20 K). The periplasmic and membrane-bound enzymes also presented additional EPR signals, observable up to 77 K, with g greater than 2.0 and assigned to nickel(III). The periplasmic hydrogenase exhibited EPR features at 2.20, 2.06 and 2.0. The signals observed in the membrane-bound preparations could be decomposed into two sets with g at 2.34, 2.16 and approximately 2.0 (component I) and at 2.33, 2.24, and approximately 2.0 (component II). In the reduced state, after exposure to an H2 atmosphere, all the hydrogenase fractions gave identical EPR spectra. EPR studies, performed at different temperatures and microwave powers, and in samples partially and fully reduced (under hydrogen or dithionite), allowed the identification of two different iron-sulfur centers: center I (2.03, 1.89 and 1.86) detectable below 10 K, and center II (2.06, 1.95 and 1.88) which was easily saturated at low temperatures. Additional EPR signals due to transient nickel species were detected with g greater than 2.0, and a rhombic EPR signal at 77 K developed at g 2.20, 2.16 and 2.0. This EPR signal is reminiscent of the Ni-signal C (g at 2.19, 2.14 and 2.02) observed in intermediate redox states of the well characterized Desulfovibrio gigas hydrogenase (Teixeira et al. (1985) J. Biol. Chem. 260, 8942]. During the course of a redox titration at pH 7.6 using H2 gas as reductant, this signal attained a maximal intensity around -320 mV. Low-temperature studies of samples at redox states where this rhombic signal develops (10 K or lower) revealed the presence of a fast-relaxing complex EPR signal with g at 2.25, 2.22, 2.15, 2.12, 2.10 and broad components at higher field. The soluble hydrogenase fractions did not show a time-dependent activation but the membrane-bound form required such a step in order to express full activity.(ABSTRACT TRUNCATED AT 400 WORDS)
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogenase/*analysis/isolation & purification; Iron-Sulfur Proteins/*analysis; Isoenzymes/*analysis/isolation & purification; Metalloproteins/*analysis; Nickel/*analysis; Oxidation-Reduction; Selenium/*analysis; Spectrophotometry, Ultraviolet; Temperature

Moessbauer study of D. gigas ferredoxin II and spin-coupling model for Fe3S4 cluster with valence delocalization - Papaefthymiou, V.; Girerd, J. J.; Moura, I.; Moura, J. J. G.; Muenck, E. (Journal of the American Chemical Society, 1987)
n/a
doi: 10.1021/ja00249a037

Evidence for the formation of a ZnFe3S4 cluster in Desulfovibrio gigas ferredoxin II - Surerus, Kristene K.; Munck, Eckard; Moura, Isabel; Moura, Jose J. G.; Legall, Jean (Journal of the American Chemical Society, 1987)
n/a
doi: 10.1021/ja00246a062

Proton NMR spectra of rubredoxins: new resonances assignable to .alpha.-CH and .beta.-CH2 hydrogens of cysteinate ligands to iron(II) - Werth, Mark T.; Kurtz, Donald M.; Moura, Isabel; Legall, Jean (Journal of the American Chemical Society, 1987)
n/a
doi: 10.1021/ja00235a042

Identification of three classes of hydrogenase in the genus, Desulfovibrio - Prickril, Benet C.; He, Shao-Hua; Li, Ching; Menon, Nanda; Choi, Eui-Sung; Przybyla, Alan E.; DerVartanian, Daniel V.; Peck Jr, Harry D.; Fauque, Guy; Legall, Jean; Teixeira, Miguel; Moura, Isabel; et al. (Biochemical and Biophysical Research Communications, 1987)
n/a
n/a

Isolation and characterization of a rubredoxin and a flavodoxin from Desulfovibrio desulfuricans Berre-Eau - Fauque, Guy D.; Moura, Isabel; Moura, José J. G.; Xavier, António V.; Galliano, Nicole; Legall, Jean (Febs Letters, 1987)
n/a
n/a
Keywords: (Desulfovibrio); Electron transfer; Flavodoxin; Rubredoxin; Sulfate reduction

Redox properties and activity studies on a nickel-containing hydrogenase isolated from a halophilic sulfate reducer Desulfovibrio salexigens - Teixeira, M.; Moura, I.; Fauque, G.; Czechowski, M.; Berlier, Y.; Lespinat, P. A.; Legall, J.; Xavier, A. V.; Moura, J. J. (Biochimie, 1986)
A soluble hydrogenase from the halophilic sulfate reducing bacterium Desulfovibrio salexigens, strain British Guiana (NCIB 8403) has been purified to apparent homogeneity with a final specific activity of 760 mumoles H2 evolved/min/mg (an overall 180-fold purification with 20% recovery yield). The enzyme is composed of two non-identical subunits of molecular masses 62 and 36 kDa, respectively, and contains approximately 1 Ni, 12-15 Fe and 1 Se atoms/mole. The hydrogenase shows a visible absorption spectrum typical of an iron-sulfur containing protein (A400/A280 = 0.275) and a molar absorbance of 54 mM-1cm-1 at 400 nm. In the native state (as isolated, under aerobic conditions), the enzyme is almost EPR silent at 100 K and below. However, upon reduction under H2 atmosphere a rhombic EPR signal develops at g-values 2.22, 2.16 and around 2.0, which is optimally detected at 40 K. This EPR signal is reminiscent of the nickel signal C (g-values 2.19, 2.16 and 2.02) observed in intermediate redox states of the well characterized D. gigas nickel containing hydrogenase and assigned to nickel by 61 Ni isotopic substitution (J.J.G. Moura, M. Teixeira, I. Moura, A.V. Xavier and J. Le Gall (1984), J. Mol. Cat., 23, 305-314). Upon longer incubation with H2 the "2.22" EPR signal decreases. During the course of a redox titration under H2, this EPR signal attains a maximal intensity around--380 mV. At redox states where this "2.22" signal develops (or at lower redox potentials), low temperature studies (below 10 K) reveals the presence of other EPR species with g-values at 2.23, 2.21, 2.14 with broad components at higher fields. This new signal (fast relaxing) exhibits a different microwave power dependence from that of the "2.22" signal, which readily saturates with microwave power (slow relaxing). Also at low temperature (8 K) typical reduced iron-sulfur EPR signals are concomitantly observed with gmed approximately 1.94. The catalytic properties of the enzyme were also followed by substrate isotopic exchange D2/H+ and H2 production measurements.
0300-9084 (Print)0300-9084 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogen/metabolism/pharmacology; Hydrogenase/analysis/*metabolism; Iron-Sulfur Proteins/analysis; Iron/analysis; Kinetics; Molecular Weight; Nickel/*analysis; Oxidation-Reduction; Selenium/analysis; Spectrophotometry; Zinc/analysis

Low-spin sulfite reductases: a new homologous group of non-heme iron-siroheme proteins in anaerobic bacteria - Moura, I.; Lino, A. R.; Moura, J. J.; Xavier, A. V.; Fauque, G.; Peck, H. D., Jr.; Legall, J. (Biochem Biophys Res Commun, 1986)
Two new low molecular weight proteins with sulfite reductase activity, isolated from Methanosarcina barkeri (DSM 800) and Desulfuromonas acetoxidans (strain 5071), were studied by EPR and optical spectroscopic techniques. Both proteins have visible spectra similar to that of the low-spin sulfite reductase of Desulfovibrio vulgaris strain Hildenborough and no band at 715 nm, characteristic of high-spin Fe3+ complexes in isobacteriochlorins is observed. EPR shows that as isolated the siroheme is in a low-spin ferric state (S = 1/2) with g-values at 2.40, 2.30 and 1.88 for the Methanosarcina barkeri enzyme and g-values at 2.44, 2.33 and 1.81 for the Desulfuromonas acetoxidans enzyme. Chemical analysis shows that both proteins contain one siroheme and one [Fe4S4] center per polypeptidic chain. These results suggest that the low molecular weight, low-spin non-heme iron siroheme proteins represent a new homologous class of sulfite reductases common to anaerobic microorganisms.
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Anaerobiosis; Bacteria/*enzymology; Desulfovibrio/enzymology; Electron Spin Resonance Spectroscopy; Euryarchaeota/enzymology; Heme/*analogs & derivatives/analysis; Iron/*analysis; Molecular Weight; Oxidation-Reduction; Oxidoreductases Acting on Sulfur Group Donors/analysis/*metabolism; Oxidoreductases/*metabolism; Spectrophotometry

Resonance Raman spectra of rubredoxin: new assignments and vibrational coupling mechanism from iron-54/iron-56 isotope shifts and variable-wavelength excitation - Czernuszewicz, Roman S.; Legall, Jean; Moura, Isabel; Spiro, Thomas G. (Inorganic Chemistry, 1986)
n/a
doi: 10.1021/ic00225a022

Evidence for the formation of a cobalt-iron-sulfur (CoFe3S4) cluster in Desulfovibrio gigas ferredoxin II - Moura, Isabel; Moura, Jose J. G.; Munck, Eckard; Papaefthymiou, Vasilios; Legall, Jean (Journal of the American Chemical Society, 1986)
n/a
doi: 10.1021/ja00262a057

Purification and characterization of three proteins from a halophilic sulfate-reducing bacterium,Desulfovibrio salexigens</i&gt - Czechowski, M.; Fauque, G.; Galliano, N.; Dimon, B.; Moura, I.; Moura, J. J. G.; Xavier, A. V.; Barato, B. A. S.; Lino, A. R.; Legall, J. (Journal of Industrial Microbiology & Biotechnology, 1986)
n/a
n/a
Keywords: Biomedical and Life Sciences

{FLASH-PHOTOLYSIS AND PULSE-RADIOLYSIS OF THE CO(SEP)3+-X- (SEP= SEPULCHRATE - Pina, F; Maestri, M; Ballardini, R; Mulazzani, Q. G.; Dangelantonio, M.; Balzani, V. (Inorganic Chemistry, 1986)
n/a
Times Cited: 14 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 14

Electron paramagnetic resonance studies on the mechanism of activation and the catalytic cycle of the nickel-containing hydrogenase from Desulfovibrio gigas - Teixeira, M.; Moura, I.; Xavier, A. V.; Huynh, B. H.; Dervartanian, D. V.; Peck, H. D., Jr.; Legall, J.; Moura, J. J. (J Biol Chem, 1985)
Desulfovibrio gigas hydrogenase (EC 1.12.2.1) is a complex enzyme containing one nickel, one 3Fe, and two [Fe4S4] clusters (Teixeira, M., Moura, I., Xavier, A. V., Der Vartanian, D. V., LeGall, J., Peck, H. D., Jr., Huynh, B. H., and Moura, J. J. G. (1983) Eur. J. Biochem. 130, 481-484). This hydrogenase belongs to a class of enzymes that are inactive "as isolated" (the so-called "oxygen-stable hydrogenases") and must go through an activation process in order to express full activity. The state of characterization of the active centers of the enzyme as isolated prompted us to do a detailed analysis of the redox patterns, activation profile, and catalytic redox cycle of the enzyme in the presence of either the natural substrate (H2) or chemical reductants. The effect of natural cofactors, as cytochrome C3, was also studied. Special focus was given to the intermediate redox species generated during the catalytic cycle of the enzyme and to the midpoint redox potentials associated. The available information is discussed in terms of a "working hypothesis" for the mechanism of the [NiFe] hydrogenases from sulfate reducing organisms in the context of activation process and catalytic cycle.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Chemical Phenomena; Chemistry; Cytochrome c Group/pharmacology; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Enzyme Activation; Iron; Nickel/*analysis; Oxidation-Reduction; Oxidoreductases/*analysis; Sulfur

Cobalt containing B12 cofactors from methanogenic bacteria - spectroscopic characterization - Lino, A. R.; Xavier, A. V.; Moura, I.; Legall, J.; Ljungdahl, P. O. (Rev Portuguesa de Química, 1985)
n/a
n/a

Nickel X-ray absorption spectroscopy of Desulvovibrio gigas hydrogenase - Scott, R. A.; Czechowski, M.; Dervartanian, D. V.; Legall, J.; Peck Jr, H. D.; Moura, I. (Rev Portuguesa de Química, 1985)
n/a
n/a

Nuclear-magnetic-resonance studies of Desulfuromonas acetoxidans cytochrome c551.5 (c7) - Moura, J. G.; Moore, G. R.; Williams, R. J.; Probst, I.; Legall, J.; Xavier, A. V. (Eur J Biochem, 1984)
1H nuclear magnetic resonance (NMR) spectroscopy has been used to examine cytochrome c551.5 (c7) from the sulfur reducer, Desulfuromonas acetoxidans. This protein contains three hemes. Two stable oxidation states (the fully oxidized and the fully reduced) as well as intermediate oxidation states were studied. The axial ligands of the iron were found to be neutral histidines. The redox properties of cytochrome c7 were examined and good quantitative agreement found between the NMR results and previously reported redox potential measurements. The properties of cytochrome c7 are discussed together with those of the homologous tetraheme cytochromes c3 isolate from sulfate-reducing bacteria.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: *Bacterial Proteins; *Cytochrome c Group; Amino Acid Sequence; Gram-Negative Anaerobic Bacteria/*analysis; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Temperature

Interconversion from 3Fe into 4Fe clusters in the presence of Desulfovibrio gigas cell extracts - Moura, J. J.; Legall, J.; Xavier, A. V. (Eur J Biochem, 1984)
Desulfovibrio gigas ferredoxin II (FdII) contains a single 3Fe cluster [Huynh, B.H., Moura, J.J.G., Moura, I., Kent, T.A., LeGall, J., Xavier, A.V., and Munck, E. (1980) J. Biol. Chem. 255, 3242-3244]. In the oxidized state the protein exhibits an intense electron paramagnetic resonance (EPR) signal at g = 2.02. Upon one-electron reduction the center becomes EPR silent. In the presence of D. gigas crude cell extracts, devoid of acidic electron carriers and supplemented with pyruvate and FdII, an EPR signal typical of reduced [4Fe-4S] centers is obtained. The appearance of this signal correlates with the beginning of stimulation of the phosphoroclastic reaction as judged by the production of H2. These results, supported by the occurrence of easy chemical conversion of the 3Fe cluster of D. gigas ferredoxin into 4Fe structures [Moura, J.J.G., Moura, I., Kent, T.A., Lipscomb, J.D., Huynh, B.H., LeGall, J., Xavier, A.V., and Munch, E. (1982) J. Biol. Chem. 257, 6259-6267], suggest that cluster conversion takes place in conditions close to the situation in vivo. This cluster interconversion is discussed in the context of some of the relevant metabolic pathways of Desulfovibrio spp.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Biotransformation; Chemical Phenomena; Chemistry; Desulfovibrio/*metabolism; Electron Spin Resonance Spectroscopy; Ferredoxins/*metabolism; Hydrogen-Ion Concentration; Iron/*metabolism; Oxidation-Reduction

NMR and electron-paramagnetic-resonance studies of a dihaem cytochrome from Pseudomonas stutzeri (ATCC 11607) (cytochrome c peroxidase) - Villalain, J.; Moura, I.; Liu, M. C.; Payne, W. J.; Legall, J.; Xavier, A. V.; Moura, J. J. (Eur J Biochem, 1984)
A dihaem cytochrome (Mr 37 400) with cytochrome c peroxidase activity was purified from Pseudomonas stutzeri (ATCC 11 607). The haem redox potentials are far apart: one of the haems is completely ascorbate-reducible and the other is only reduced by dithionite. The coordination, spin states and redox properties of the covalently bound haems were probed by visible, NMR and electron paramagnetic resonance (EPR) spectroscopies in three oxidation states. In the oxidized state, the low-temperature EPR spectrum of the native enzyme is a complex superimposition of three components: (I) a low-spin haem indicating a histidinyl-methionyl coordination; (II) a low-spin haem indicating a histidinyl-histidinyl coordination; and (III) a minor high-spin haem component. At room temperature, NMR and optical studies indicate the presence of high-spin and low-spin haems, suggesting that for one of the haems a high-spin to low-spin transition is observed when temperature is decreased. In the half-reduced state, the component I (high redox potential) of the EPR spectrum disappears and induces a change in the g-values and linewidth of component II; the high-spin component II is no longer detected at low temperature. Visible and NMR studies reveal the presence of a high-spin ferric and a low-spin (methionyl-coordinated) ferrous state. The NMR data fully support the haem-haem interaction probed by EPR. In the reduced state, the NMR spectrum indicates that the low-potential haem is high-spin ferrous.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Chemical Phenomena; Chemistry; Cyanides; Cytochrome-c Peroxidase/*metabolism; Electron Spin Resonance Spectroscopy; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Oxidation-Reduction; Peroxidases/*metabolism; Pseudomonas/*enzymology; Temperature

NMR studies of a dihaem cytochrome from Pseudomonas perfectomarinus (ATCC 14405) - Moura, I.; Liu, M. C.; Legall, J.; Peck, H. D., Jr.; Payne, W. J.; Xavier, A. V.; Moura, J. J. (Eur J Biochem, 1984)
Pseudomonas perfectomarinus (ATCC 14405) dihaem cytochrome c552 was studied by 300-MHz proton magnetic resonance. Some of the haem resonances were assigned in the fully reduced and fully oxidized states. No evidence was found for methionine haem axial coordination. The oxidation-reduction equilibrium was studied in detail. Due to the large difference in mid-point redox potential between the two haems (+174 mV, for haem II and -180 mV for haem I) an intermediate oxidation state could be obtained containing reduced haem I and oxidized haem II. In this way the total paramagnetic shift at different oxidation levels could be decomposed in the intrinsic and extrinsic contributions. It was found that the two haems interact. The rate of electron exchange is slow on the NMR time scale. The redox equilibria are discussed for four possible redox species in solution.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Chemical Phenomena; Chemistry; Cytochrome c Group/*metabolism; Heme; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Models, Chemical; Oxidation-Reduction; Pseudomonas/*enzymology; Temperature

NMR studies of electron transfer mechanisms in a protein with interacting redox centres: Desulfovibrio gigas cytochrome c3 - Santos, H.; Moura, J. J.; Moura, I.; Legall, J.; Xavier, A. V. (Eur J Biochem, 1984)
The proton NMR spectra of the tetrahaem cytochrome c3 from Desulfovibrio gigas were examined while varying the pH and the redox potential. The analysis of the NMR reoxidation pattern was based on a model for the electron distribution between the four haems that takes into account haem-haem redox interactions. The intramolecular electron exchange is fast on the NMR time scale (larger than 10(5) s-1). The NMR data concerning the pH dependence of the chemical shift of haem methyl resonances in different oxidation steps and resonance intensities are not compatible with a non-interacting model and can be explained assuming a redox interaction between the haems. A complete analysis at pH* = 7.2 and 9.6, shows that the haem-haem interacting potentials cover a range from -50 mV to +60 mV. The midpoint redox potentials of some of the haems, as well as some of their interacting potentials, are pH-dependent. The physiological relevance of the modulation of the haem midpoint redox potentials by both the pH and the redox potential of the solution is discussed.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Chemical Phenomena; Chemistry; Cytochrome c Group/*metabolism; Desulfovibrio/*enzymology; Electron Transport; Heme/metabolism; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Mathematics; Models, Chemical; Oxidation-Reduction; Protons

Purification, characterization and redox properties of hydrogenase from Methanosarcina barkeri (DSM 800) - Fauque, G.; Teixeira, M.; Moura, I.; Lespinat, P. A.; Xavier, A. V.; Dervartanian, D. V.; Peck, H. D., Jr.; Legall, J.; Moura, J. G. (Eur J Biochem, 1984)
A soluble hydrogenase from the methanogenic bacterium, Methanosarcina barkeri (DSM 800) has been purified to apparent electrophoretic homogeneity, with an overall 550-fold purification, a 45% yield and a final specific activity of 270 mumol H2 evolved min-1 (mg protein)-1. The hydrogenase has a high molecular mass of approximately equal to 800 kDa and subunits with molecular masses of approximately equal to 60 kDa. The enzyme is stable to heating at 65 degrees C and to exposure to air at 4 degrees C in the oxidized state for periods up to a week. The overall stability of this enzyme is compared with other hydrogenase isolated from strict anaerobic sulfate-reducing bacteria. Ms. barkeri hydrogenase shows an absorption spectrum typical of a non-heme iron protein with maxima at 275 nm, 380 nm and 405 nm. A flavin component, identified as FMN or riboflavin was extracted under acidic conditions and quantified to approximately one flavin molecule per subunit. In addition to this component, 8-10 iron atoms and 0.6-0.8 nickel atom were also detected per subunit. The electron paramagnetic resonance (EPR) spectrum of the native enzyme shows a rhombic signal with g values at 2.24, 2.20 and approximately equal to 2.0. probably due to nickel which is optimally measured at 40 K but still detectable at 77 K. In the reduced state, using dithionite or molecular hydrogen as reductants, at least two types of g = 1.94 EPR signals, due to iron-sulfur centers, could be detected and differentiated on the basis of power and temperature dependence. Center I has g values at 2.04, 1.90 and 1.86, while center II has g values at 2.08, 1.93 and 1.85. When the hydrogenase is reduced by hydrogen or dithionite the rhombic EPR species disappears and is replaced by other EPR-active species with g values at 2.33, 2.23, 2.12, 2.09, 2.04 and 2.00. These complex signals may represent different nickel species and are only observable at temperatures higher than 20 K. In the native preparation, at high temperatures (T greater than 35 K) or in partially reduced samples, a free radical due to the flavin moiety is observed. The EPR spectrum of reduced hydrogenase in 80% Me2SO presents an axial type of spectrum only detectable below 30 K.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Allosteric Site; Electron Spin Resonance Spectroscopy; Euryarchaeota/*enzymology; Hydrogenase; Molecular Weight; Oxidation-Reduction; Oxidoreductases/*isolation & purification/metabolism; Spectrum Analysis

Molybdenum EXAFS of the Desulfovibrio gigas Mo(2Fe-2S) protein--structural similarity to "desulfo" xanthine dehydrogenase - Cramer, S. P.; Moura, J. J.; Xavier, A. V.; Legall, J. (J Inorg Biochem, 1984)
The molybdenum EXAFS of the Mo(2Fe-2S) protein from Desulfovibrio gigas has been examined using fluorescence detection and synchrotron radiation. In the oxidized form the molybdenum environment is found to contain two terminal oxo groups and two long (2.47 A) Mo-S bonds. Evidence was also found for an oxygen or nitrogen donor ligand at 1.90 A. Addition of dithionite to the oxidized enzyme results in loss of a terminal oxo group, perhaps due to protonation. In addition, a 0.1 A contraction in the Mo-S bond lengths is observed. The behavior of both oxidized and dithionite-treated forms is similar to that observed previously with "desulfo" xanthine oxidase.
0162-0134 (Print)0162-0134 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: *Bacterial Proteins; *Iron-Sulfur Proteins; *Metalloproteins; Desulfovibrio/*analysis; Electron Spin Resonance Spectroscopy; Molybdenum; Protein Conformation; Xanthine Dehydrogenase

X-ray absorption spectroscopy of nickel in the hydrogenase from Desulfovibrio gigas - Scott, Robert A.; Wallin, Sten A.; Czechowski, Melvin; Dervartanian, D. V.; Legall, Jean; Peck, Harry D.; Moura, Isabel (Journal of the American Chemical Society, 1984)
n/a
doi: 10.1021/ja00334a078

ESR studies of cytochrome c3 from Desulfovibrio desulfuricans strain Norway 4: Midpoint potentials of the four haems, and interactions with ferredoxin and colloidal sulphur - Cammack, R.; Fauque, G.; Moura, J. J. G.; Legall, J. (Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1984)
n/a
n/a
Keywords: (D. desulfuricans); Cytochrome c3; ESR; Heme redox potential

Nickel - a redox catalytic site in hydrogenase - Moura, J. J. G.; Teixeira, M.; Moura, I.; Xavier, A. V.; Legall, J. (Journal of Molecular Catalysis, 1984)
n/a
n/a

Nuclear-magnetic-resonance studies of Desulfuromonas acetoxidans cytochrome c551.5 (c7) - Moura, José J. G.; Moore, Geoffrey R.; Williams, Robert J. P.; Probst, Irmelin; Legall, Jean; Xavier, António V. (European Journal of Biochemistry, 1984)
1H nuclear magnetic resonance (NMR) spectroscopy has been used to examine cytochrome c551.5 (c7) from the sulfur reducer, Desulfuromonas acetoxidans. This protein contains three hemes. Two stable oxidation states (the fully oxidized and the fully reduced) as well as intermediate oxidation states were studied. The axial ligands of the iron were found to be neutral histidines. The redox properties of cytochrome c7 were examined and good quantitative agreement found between the NMR results and previously reported redox potential measurements. The properties of cytochrome c7 are discussed together with those of the homologous tetraheme cytochromes c3 isolate from sulfate-reducing bacteria.
n/a

PHOTOCHEMICAL REACTIVITY OF BIS-CYCLOPENTADIENYL METAL-COMPLEXES M(ETA-5-C5H5)2X2 N+(N=0,1 - M=MO, W - X=CL, BR, L) - Calhorda, M. J.; Costa, S. M. B.; Dias, A. R.; Pina, F. J. S. (Nouveau Journal De Chimie-New Journal of Chemistry, 1984)
n/a
Times Cited: 2 Costa, Silvia/H-7766-2012; Costa, Silvia/M-8085-2013 Costa, Silvia/0000-0002-6978-8903 2

Desulfovibrio Gigas hydrogenase: redox properties of the nickel and iron-sulfur centers - Teixeira, M.; Moura, I.; Xavier, A. V.; Dervartanian, D. V.; Legall, J.; Peck, H. D., Jr.; Huynh, B. H.; Moura, J. J. (Eur J Biochem, 1983)
Below 30 K, oxidized Desulfovibrio gigas hydrogenase presents an intense electron paramagnetic resonance (EPR) signal centered at g = 2.02, typical of an iron-sulfur center. In addition a rhombic EPR signal, attributed to Ni(III) species, is also observed [LeGall, J., Ljungdahl, P., Moura, I., Peck, H.D., Jr, Xavier, A.V., Moura, J.J.G., Teixeira, M., Huynh, B.H., and DerVartanian, D.V. (1982) Biochem. Biophys. Res. Commun. 106, 610-616; and Cammack, R., Patil, D., Aguirre, R., and Hatchikian, E.C., (1982) FEBS Lett. 142, 289-292]. At higher temperatures (77 K) the iron-sulfur EPR signal is broader and all the EPR features of the rhombic nickel signal can easily be observed. We have now obtained additional information concerning the redox properties of these EPR active centers, using an EPR redox titration method in the presence of dye mediators at pH = 8.5. The mid-point potential was determined to be -70 mV for the Fe,S cluster and -220 mV for the Ni center. Intermediate oxidation states were obtained upon partial reduction with either dithionite or hydrogen. Although upon dithionite reduction the centers are reduced in the order of decreasing mid-point reduction potentials, under a hydrogen atmosphere the nickel center reduces preferentially. This suggests a catalytic involvement of the nickel redox center in the binding of hydrogen. Preliminary Mossbauer studies on Desulfovibrio gigas hydrogenase reveal the presence of a paramagnetic 3 Fe center and two 4 Fe centers. The 3 Fe center is responsible for the g = 2.02 EPR signal but the two 4 Fe centers have been so far undetectable by EPR.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Bacterial Proteins/*isolation & purification; Chemical Phenomena; Chemistry; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogenase; Iron-Sulfur Proteins/*analysis; Metalloproteins/*analysis; Nickel/*analysis; Oxidation-Reduction; Oxidoreductases/*isolation & purification

Resonance Raman spectra of rubredoxin, desulforedoxin, and the synthetic analog Fe(S2-o-xyl)2: conformational effects - Yachandra, Vittal K.; Hare, Jeffrey; Moura, I.; Spiro, Thomas G. (Journal of the American Chemical Society, 1983)
n/a
doi: 10.1021/ja00359a015

Electron transfer mechanism studies of cytochrome c3: pH dependence of the redox equilibria - Santos, H.; Moura, J. J. G.; Xavier, A. V.; Legall, J. (Inorganica Chimica Acta, 1983)
n/a
n/a

Mössbauer and EPR evidence for nickel and 3Fe cluster in the hydrogenases of D. desulfuricans and D. gigas - Huynh, B. H.; Legall, J.; Dervartanian, D. V.; Peck Jr, H. D.; Krüger, H. J.; Moura, I.; Moura, J. J. G.; Xavier, A. V. (Inorganica Chimica Acta, 1983)
n/a
n/a

Nickel containing hydrogenases - Xavier, A. V.; Teixeira, M.; Moura, I.; Moura, J. J. G.; Legall, J. (Inorganica Chimica Acta, 1983)
n/a
n/a

Proteins containing the factor F430 from methanosarcina barkeri and methanobacterium thermoautotrophicum: Isolation and properties - Moura, Isabel; Moura, José J. G.; Santos, Helena; Xavier, Antonio V.; Burch, Gary; Peck Jr, Harry D.; Legall, Jean (Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1983)
n/a
n/a
Keywords: F430; Methanogenic bacterium; Nickel protein

NMR redox studies of Desulfovibrio vulgaris Cytochrome c3. Electron transfer mechanisms - Moura, J. J.; Santos, H.; Moura, I.; Legall, J.; Moore, G. R.; Williams, R. J.; Xavier, A. V. (Eur J Biochem, 1982)
The 300-MHz proton NMR spectra of the tetrahaem cytochrome c3 from Desulfovibrio vulgaris were examined while varying the pH and the redox potential. The analysis of the complete NMR reoxidation pattern was done taking into account all the 16 redox states that can be present in the redox titration of a tetra-redox-center molecule. A network of saturation transfer experiments performed at different oxidation stages, between the fully reduced and the fully oxidized states, allowed the observation of different resonances for some of the haem methyl groups. In the present experimental conditions, some of the haems show a fast intramolecular electron exchange rate, but the intermolecular electron exchange is always slow. In intermediate reoxidation stages, large shifts of the resonances of some haem methyl groups were observed upon changing the pH. These shifts are discussed in terms of a pH dependence of the haem midpoint redox potentials. The physiological relevance of this pH dependence is discussed.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Chemical Phenomena; Chemistry; Cytochrome c Group/*metabolism; Desulfovibrio/*enzymology; Magnetic Resonance Spectroscopy; Oxidation-Reduction

Unambiguous identification of the nickel EPR signal in 61Ni-enriched Desulfovibrio gigas hydrogenase - Moura, J. J.; Moura, I.; Huynh, B. H.; Kruger, H. J.; Teixeira, M.; DuVarney, R. C.; Dervartanian, D. V.; Xavier, A. V.; Peck, H. D., Jr.; Legall, J. (Biochem Biophys Res Commun, 1982)
n/a
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Binding Sites; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogenase; Nickel/*analysis; Oxidoreductases/isolation & purification/*metabolism; Protein Binding

Isolation of P590 from Methanosarcina barkeri: evidence for the presence of sulfite reductase activity - Moura, J. J.; Moura, I.; Santos, H.; Xavier, A. V.; Scandellari, M.; Legall, J. (Biochem Biophys Res Commun, 1982)
n/a
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Euryarchaeota/*analysis; Hydrogen-Ion Concentration; Hydrogen/metabolism; Molecular Weight; Oxidoreductases Acting on Sulfur Group Donors/*isolation &; Oxidoreductases/*isolation & purification/*metabolism; purification/*metabolism; Spectrophotometry, Ultraviolet

The presence of redox-sensitive nickel in the periplasmic hydrogenase from Desulfovibrio gigas - Legall, J.; Ljungdahl, P. O.; Moura, I.; Peck, H. D., Jr.; Xavier, A. V.; Moura, J. J.; Teixera, M.; Huynh, B. H.; Dervartanian, D. V. (Biochem Biophys Res Commun, 1982)
n/a
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogenase; Nickel/*analysis; Oxidation-Reduction; Oxidoreductases/*isolation & purification/metabolism

Iron-sulphur cluster composition and redox properties of two ferredoxins from Desulfovibrio desulfuricans Norway strain - Guerlesquin, F.; Moura, J. J.; Cammack, R. (Biochim Biophys Acta, 1982)
Two ferredoxins from Desulfovibrio desulfuricans, Norway Strain, were investigated by EPR spectroscopy. Ferredoxin I appears to be a conventional [4Fe-4S]2+;1+ ferredoxin, with a midpoint reduction potential of -374 mV at pH 8. Ferredoxin II when reduced, at first showed a more complex spectrum, indicating an interaction between two [4Fe-4S] clusters, and probably, has two clusters per protein subunit. Upon reductive titration ferredoxin II changed to give a spectrum in which no intercluster interaction was seen. The midpoint potentials of the native and modified ferredoxin at pH 8 were estimated to be -500 and -440 mV, respectively.
0006-3002 (Print)0006-3002 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: *Ferredoxins; Desulfovibrio/*analysis; Electron Spin Resonance Spectroscopy; Iron; Oxidation-Reduction; Sulfur

Core dimensions in the 3Fe cluster of Desulfovibrio gigas ferredoxin II by extended X-ray absorption fine structure spectroscopy - Antonio, M. R.; Averill, B. A.; Moura, I.; Moura, J. J.; Orme-Johnson, W. H.; Teo, B. K.; Xavier, A. V. (J Biol Chem, 1982)
We have obtained the iron K-edge extended X-ray adsorption fine structure spectra of the 3Fe ferredoxin II of Desulfovibrio gigas in the oxidized and reduced states. For both states, interpretation of the EXAFS data suggests that the Fe-S first shell coordination distance is near 2.25 A, in agreement with crystallographic studies of model compounds and proteins containing 2Fe-2S and 4Fe-4S centers, as well as with a recent crystallographic study of Azotobacter vinelandii ferredoxin I (Ghosh, D., Furey, W., Jr., O'Donnell, S., and Stout, C. D. (1981) J. Biol. Chem. 256, 4185-4192). The apparent Fe-Fe distance we obtain for the desulfovibrio protein (2.7 A) also agrees with similar distances seen in other Fe-S centers, except with the 3Fe cluster in the Azotobacter vinelandii ferredoxin I structure, for which an Fe-Fe distance of 4.2 A was reported. We conclude that either the two 3Fe ferredoxins have substantially different core dimensions, a possibility apparently unique to 3Fe centers among known Fe-S systems in proteins, or that one (or more) of the structural studies is in substantial error.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: *Ferredoxins; Desulfovibrio/*metabolism; Fourier Analysis; Iron/*analysis; Protein Binding; Protein Conformation; Spectrum Analysis

Incorporation of cytoplasmic vesicles into apical membrane of mammalian urinary bladder epithelium - Lewis, S. A.; de Moura, J. L. (Nature, 1982)
n/a
0028-0836 (Print)0028-0836 (Linking)Journal ArticleResearch Support, U.S. Gov't, P.H.S.
Keywords: Animals; Cell Membrane/physiology; Colchicine/pharmacology; Cytochalasin B/pharmacology; Cytoplasmic Granules/physiology; Electric Conductivity; Ion Channels/*metabolism; Membrane Fusion; Rabbits; Stress, Mechanical; Urinary Bladder/*physiology/ultrastructure

Interconversions of [3Fe-3S] and [4Fe-4S] clusters. Mossbauer and electron paramagnetic resonance studies of Desulfovibrio gigas ferredoxin II - Moura, J. J.; Moura, I.; Kent, T. A.; Lipscomb, J. D.; Huynh, B. H.; Legall, J.; Xavier, A. V.; Munck, E. (J Biol Chem, 1982)
n/a
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Desulfovibrio/*metabolism; Electron Spin Resonance Spectroscopy; Ferredoxins/*metabolism; Iron/*metabolism; Kinetics; Spectrum Analysis; Sulfur/*metabolism

Evidence for nickel and a three-iron center in the hydrogenase of Desulfovibrio desulfuricans - Kruger, H. J.; Huynh, B. H.; Ljungdahl, P. O.; Xavier, A. V.; Dervartanian, D. V.; Moura, I.; Peck, H. D., Jr.; Teixeira, M.; Moura, J. J.; Legall, J. (J Biol Chem, 1982)
Hydrogenase from Desulfovibrio desulfuricans (ATCC No. 27774) grown in unenriched and in enriched 61Ni and 57Fe media has been purified to apparent homogeneity. Two fractions of enzymes with hydrogenase activity were separated and were termed hydrogenase I and hydrogenase II. they were shown to have similar molecular weights (77,600 for hydrogenase I and 75,500 for hydrogenase II), to be composed of two polypeptide chains, and to contain Ni and non-heme iron. Because of its higher specific activity (152 versus 97) hydrogenase II was selected for EPR and Mossbauer studies. As isolated, hydrogenase II exhibits an "isotropic" EPR signal at g = 2.02 and a rhombic EPR signal at g = 2.3, 2.2, and 2.0. Isotopic substitution of 61Ni proves that the rhombic signal is due to Ni. Combining the Mossbauer and EPR data, the isotropic g = 2.02 EPR signal was shown to originate from a 3Fe cluster which may have oxygenous or nitrogenous ligands. In addition, the Mossbauer data also revealed two [4Fe-4S]2+ clusters iun each molecule of hydrogenase II. The EPR and Mossbauer data of hydrogenase I were found to be identical to those of hydrogenase II, indicating that both enzymes have common metallic centers.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogenase; Iron/*analysis; Nickel/*analysis; Oxidoreductases/*isolation & purification/metabolism; Spectrum Analysis

Amino acid sequence of a 3Fe:3S ferredoxin from the "archaebacterium" Methanosarcina barkeri (DSM 800) - Hausinger, R. P.; Moura, I.; Moura, J. J.; Xavier, A. V.; Santos, M. H.; Legall, J.; Howard, J. B. (J Biol Chem, 1982)
The complete amino acid sequence for a 3Fe:3S ferredoxin from the "archaebacterium" Methanosarcina barkeri (DSM 800) was determined by repetitive Edman degradation on the whole protein and peptides derived from trypsin, thermolysin, and Staphylococcus aureus protease digestion. The protein has 59 residues of which 8 are cysteines. The latter have the same spacing and distribution as found for the clostridial-type 2 x 4Fe:4S ferredoxins. Also, the sequence had evidence of internal homology which is indicative of gene duplication prior to the divergence of the archaebacteria and the eubacteria. This is the first sequence to be reported for a methanogen ferredoxin and only the fourth for a 3Fe:3S ferredoxin from any source.
0021-9258 (Print)0021-9258 (Linking)Comparative StudyJournal ArticleResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: *Ferredoxins; Amino Acid Sequence; Endopeptidases; Euryarchaeota/*analysis; Peptide Fragments/analysis; Species Specificity

Mossbauer and EPR studies on nitrite reductase from Thiobacillus denitrificans - Huynh, B. H.; Lui, M. C.; Moura, J. J.; Moura, I.; Ljungdahl, P. O.; Munck, E.; Payne, W. J.; Peck, H. D., Jr.; Dervartanian, D. V.; Legall, J. (J Biol Chem, 1982)
n/a
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: *Electron Spin Resonance Spectroscopy; *NADH, NADPH Oxidoreductases/analysis; *Nitrite Reductases/analysis; *Spectrometry, Gamma; Heme/analysis; Molecular Weight; Oxidation-Reduction; Spectrophotometry; Thiobacillus/*enzymology

Ferredoxin from Methanosarcina barkeri: evidence for the presence of a three-iron center - Moura, I.; Moura, J. J.; Huynh, B. H.; Santos, H.; Legall, J.; Xavier, A. V. (Eur J Biochem, 1982)
Methanosarcina barkeri ferredoxin was purified and characterized by electron paramagnetic resonance (EPR) and Mossbauer spectroscopy. The purification procedure included chromatographic steps on DEAE-cellulose and gel filtration. The isolated protein is unstable under aerobic conditions. The ferredoxin exhibits charge transfer bands at 283 nm and 405 nm with an absorption ratio A405/A283 = 0.73. Its molecular weight has been estimated to be 20000-22000 by gel filtration chromatography. The native ferredoxin exhibits an intense EPR signal at g = 2.02 and only a very weak g = 1.94 signal develops upon reduction with dithionite. The Mossbauer spectra of the reduced protein are characteristic of a [3Fe-3S] center. The combined EPR and Mossbauer studies show that M. barkeri ferredoxin contains only [3Fe-3S] clusters, similar to Azotobacter vinelandii Fd[Emptage, M.H., Kent, T.A., Huynh, B.H., Rawlings, J., Orme-Johnson, W.H. & Munck, M. (1980) J. Biol. Chem. 255, 1793-1796], Desulfovibrio gigas FdII [Huynh, B.H., Moura, J.J.G., Moura, I., Kent, T.A., LeGall, J., Xavier, A.V. & Munck, E. (1980) J. Biol. Chem. 255, 3242-3244] and mitochondrial beef heart aconitase [Kent, T.A., Dreyer, J.-L., Kennedy, M.C., Huynh, B.H., Emptage, M.H., Beinert, H. & Munck, E. (1982) Proc. Natl Acad. Sci. USA, 79, 1096-1100].
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Chemical Phenomena; Chemistry; Electron Spin Resonance Spectroscopy; Euryarchaeota/*analysis; Ferredoxins/*isolation & purification; Iron/*isolation & purification; Spectrum Analysis/methods

Role of vitamin B12 in methyl transfer for methane biosynthesis by Methanosarcina barkeri - Wood, J. M.; Moura, I.; Moura, J. J.; Santos, M. H.; Xavier, A. V.; Legall, J.; Scandellari, M. (Science, 1982)
When Methanosarcina barkeri is grown on methanol as the sole carbon source, a B12-containing protein is synthesized by this organism. This B12 protein contains bound aquocobalamin, and when this cofactor is reduced and methylated with [14C]methyl iodide, the resultant [14C]methyl B12 protein is extremely active in the biosynthesis of 14C-labeled methane. These findings indicate that a B12-dependent system is operative in the biological formation of methane in addition to other systems that are B12-independent.
0036-8075 (Print)0036-8075 (Linking)Journal ArticleResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.
Keywords: Bacterial Proteins/metabolism; Euryarchaeota/*metabolism; Methane/*biosynthesis; Methanol/metabolism; Vitamin B 12/*metabolism