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1991
Lai, KK, Moura I, Liu MY, Legall J, To Yue K.  1991.  Direct evidence of the metal-free nature of sirohydrochlorin in desulfoviridin. Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1060:25-27., Number 1 AbstractWebsite
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Coito, FJ, Lemos JM.  1991.  A long-range adaptive controller for robot manipulators. The International journal of robotics research. 10:684–707., Number 6: Sage Publications Abstract

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1990
Lampreia, J, Moura I, Teixeira M, Peck, H. D. J, Legall J, Huynh BH, Moura JJ.  1990.  The active centers of adenylylsulfate reductase from Desulfovibrio gigas. Characterization and spectroscopic studies, Mar 30. Eur J Biochem. 188:653-64., Number 3 AbstractWebsite

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.

Moura, I, Tavares P, Moura JJ, Ravi N, Huynh BH, Liu MY, Legall J.  1990.  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, Dec 15. J Biol Chem. 265:21596-602., Number 35 AbstractWebsite

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.

Costa, C, Macedo A, Moura I, Moura JJ, Legall J, Berlier Y, Liu MY, Payne WJ.  1990.  Regulation of the hexaheme nitrite/nitric oxide reductase of Desulfovibrio desulfuricans, Wolinella succinogenes and Escherichia coli. A mass spectrometric study, Dec 10. FEBS Lett. 276:67-70., Number 1-2 AbstractWebsite

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.

Costa, C, Moura JJ, Moura I, Liu MY, Peck, H. D. J, Legall J, Wang YN, Huynh BH.  1990.  Hexaheme nitrite reductase from Desulfovibrio desulfuricans. Mossbauer and EPR characterization of the heme groups, Aug 25. J Biol Chem. 265:14382-8., Number 24 AbstractWebsite

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.

Fauque, G, Lino AR, Czechowski M, Kang L, Dervartanian DV, Moura JJ, Legall J, Moura I.  1990.  Purification and characterization of bisulfite reductase (desulfofuscidin) from Desulfovibrio thermophilus and its complexes with exogenous ligands, Aug 1. Biochim Biophys Acta. 1040:112-8., Number 1 AbstractWebsite

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).

Teixeira, M, Moura I, Fauque G, Dervartanian DV, Legall J, Peck, H. D. J, Moura JJ, Huynh BH.  1990.  The iron-sulfur centers of the soluble [NiFeSe] hydrogenase, from Desulfovibrio baculatus (DSM 1743). EPR and Mossbauer characterization, Apr 30. Eur J Biochem. 189:381-6., Number 2 AbstractWebsite

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.

Saraiva, LM, Liu MY, Payne WJ, Legall J, Moura JJ, Moura I.  1990.  Spin-equilibrium and heme-ligand alteration in a high-potential monoheme cytochrome (cytochrome c554) from Achromobacter cycloclastes, a denitrifying organism, Apr 30. Eur J Biochem. 189:333-41., Number 2 AbstractWebsite

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.

Dionísio, M, Ramos MJJ, Gonçalves RM.  1990.  The enthalpy and entropy of cavity formation in liquids and corresponding states principle. Canadian Journal of Chemistry. 68:1937-1949.Website
Dionísio, M, Almeida LN, Ramos MJ.  1990.  The n-alkane solvent effect on the dipole moment of the trans-1,2-dibromocyclohexane. Bulletin des Sociétés Chimiques Belges. 99(4):215-220.Website
A.G., B.  1990.  Programmable Cardiac Simulator. 2nd Portuguese Congress of Biomedical Engineering. , Aveiro Abstract

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Batista, AG.  1990.  Programmable Cardiac Simulator. Abstract

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FIGUEIREDO, P, Pina F, Vilasboas L, Macanita AL.  1990.  FLUORESCENCE-SPECTRA AND DECAYS OF MALVIDIN 3,5-DIGLUCOSIDE IN AQUEOUS-SOLUTIONS. Journal of Photochemistry and Photobiology a-Chemistry. 52:411-424., Number 3 AbstractWebsite
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Simões Gonçalves, MLS, Lopes da Conceição AC, Moura JJG.  1990.  Metal ion binding of copper(II), zinc(II) and lead(II) to cytochrome C. Electrochimica Acta. 35:473-478., Number 2 AbstractWebsite
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Pina, F, Sotomayor J, Moggi L.  1990.  PHOTOCHEMISTRY OF THE CO(SEP)3+-I- SYSTEM - EVALUATION OF THE QUANTUM YIELD FOR THE PHOTOCHEMICAL REDOX REACTION OF THE ION-PAIR. Journal of Photochemistry and Photobiology a-Chemistry. 53:411-422., Number 3 AbstractWebsite
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A.G., B.  1990.  Programmable Cardiac Simulator. 2nd Portuguese Congress of Biomedical Engineering. , Aveiro Abstract
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Batista, AG.  1990.  Programmable Cardiac Simulator. 2nd Portuguese Congress of Biomedical Engineering. Abstract
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1989
Moniz, A.  1989.  MODERNIZAÇÃO DA INDÚSTRIA PORTUGUESA: Análise de um inquérito sociológico[Modernization of Portuguese Industry: Analysis of a sociological survey], Sep. , Number 6968: University Library of Munich, Germany Abstract

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.

Moniz, A.  1989.  {MODERNIZAÇÃO DA INDÚSTRIA PORTUGUESA: Análise de um inquérito sociológico[Modernization of Portuguese Industry: Analysis of a sociological survey]}, Sep. , Number 6968: University Library of Munich, Germany Abstract

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.

Teixeira, M, Moura I, Xavier AV, Moura JJ, Legall J, Dervartanian DV, Peck, H. D. J, Huynh BH.  1989.  Redox intermediates of Desulfovibrio gigas [NiFe] hydrogenase generated under hydrogen. Mossbauer and EPR characterization of the metal centers, Oct 5. J Biol Chem. 264:16435-50., Number 28 AbstractWebsite

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.

Stewart, DE, Legall J, Moura I, Moura JJ, Peck, H. D. J, Xavier AV, Weiner PK, Wampler JE.  1989.  Electron transport in sulfate-reducing bacteria. Molecular modeling and NMR studies of the rubredoxin--tetraheme-cytochrome-c3 complex, Nov 20. Eur J Biochem. 185:695-700., Number 3 AbstractWebsite

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.

Moura, JJG, Teixeira M, Moura I.  1989.  The Role Of Nickel And Iron Sulfur Centers In The Bioproduction Of Hydrogen, May. Pure and Applied Chemistry. 61:915-921., Number 5 AbstractWebsite
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Gadsby, PM, Hartshorn RT, Moura JJ, Sinclair-Day JD, Sykes AG, Thomson AJ.  1989.  Redox properties of the diheme cytochrome c4 from Azotobacter vinelandii and characterisation of the two hemes by NMR, MCD and EPR spectroscopy, Jan 19. Biochim Biophys Acta. 994:37-46., Number 1 AbstractWebsite

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.

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