Photochemistry of supramolecular species involving anionic coordination compounds and polyammonium macrocyclic receptors - Pina, F; A. J. Parola (Coordination Chemistry Reviews, 1999)
Polyammonium macrocyclic receptors can bind anionic coordination compounds, namely those containing cyanide ligands. The;driving force to maintain the adduct is essentially the coulombic attraction, but the possibility of formation of hydrogen bonds is also important to define the geometry of the structure. The second coordination sphere that results from the binding of the polyammonium macrocycle can change several physicochemical properties of the metal coordination-compound, such as spectroscopic, redox and photophysical properties as well as the photochemical reactivity. These. changes permit:to infer, in some favourable cases, details of the supramolecular structure in solution. (C) 1999 Elsevier Science S.A. All rights reserved.
ISI Document Delivery No.: 203GXTimes Cited: 22 Cited Reference Count: 33 Pina, F Parola, AJ XXXIII International Conference on Coordination Chemistry Aug 30-sep 04, 1998 Florence, italy Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Elsevier science sa Lausanne

Tetracarboxylatodirhenium complexes linked by axial cyano bridges to metalpentacarbonyl ligands - Synthesis and characterization - Kuhn, F. E.; Goncalves, I. S.; Lopes, A. D.; Lopes, J. P.; Romao, C. C.; Wachter, W.; Mink, J.; Hajba, L.; A. J. Parola; Pina, F; J. Sotomayor (European Journal of Inorganic Chemistry, 1999)
Reaction of Re-2{mu-O2CC(CH3)(3)}(4)Cl-2 with [(CO)(5)M-CN]Na (M = Cr, Mo, W) leads to tetranuclear complexes of formula Re-2{mu-O2CC(CH3)(3)}(4)[-NC-M(CO)(5)](2) (M = Cr, Mo, W). These complexes were characterized by H-1-, C-13-, and Mo-95-NMR, IR and Raman spectroscopy, elemental analysis and examined by cyclic voltammetry. The applied methods show the donor capabilities of the [(CO)(5)M-CN](-) ligands which shift electron density towards the Re centers weakening the Re-Re quadruple bond. The Re-Re bond lengths and the v(Re-Re) force constants are estimated based on the FT-IR and Raman examinations. Photochemical examinations and TG/MS experiments have also been conducted. The latter methods shows that the product complexes decompose around 100 degrees C, by first loosing their carbonyl substituents; as do the Cr, Mo, W precursor compounds. The dirhenium tetrapivalate unit decomposes only at higher temperatures in a distinct second step.
ISI Document Delivery No.: 161EKTimes Cited: 17 Cited Reference Count: 42 Kuhn, FE Goncalves, IS Lopes, AD Lopes, JP Romao, CC Wachter, W Mink, J Hajba, L Parola, AJ Pina, F Sotomayor, J Kuhn, Fritz/A-3113-2010; Pina, Fernando/C-8161-2011; Lopes, Andre/E-2136-2012; Romao, Carlos /D-1162-2010; Parola, A. Jorge/F-4048-2010; Sotomayor, Joao/D-8103-2013; Goncalves, Isabel/H-3742-2013 Romao, Carlos /0000-0001-5061-3743; Parola, A. Jorge/0000-0002-1333-9076; Sotomayor, Joao/0000-0002-4589-0591; Wiley-v c h verlag gmbh Berlin

Antibiotic resistance as a stress response: complete sequencing of a large number of chromosomal loci in Staphylococcus aureus strain COL that impact on the expression of resistance to methicillin - H. de Lencastre; S.W Wu; M. G. Pinho; A. M. Ludovice; S. Filipe; S. Gardete; R. Sobral; S. Gill; M. Chung; A. Tomasz (Microb. Drug Resist, 1999)

Comparing dielectric measurements on poly(ethylene terephthalate) at constant heating rates with isothermal measurements - M. Dionísio; N. M. Alves; J.F. Mano (Polymer, 1999)

ADVANCES IN INORGANIC CHEMISTRY, VOL 47 (1999)
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Biochemical and spectroscopic characterization of overexpressed fuscoredoxin from Escherichia coli - Pereira, A. S.; Tavares, P; Krebs, C.; Huynh, B. H.; Rusnak, F.; Moura, I.; Moura, J. J. G. (Biochemical And Biophysical Research Communications, 1999)
Fuscoredoxin is a unique iron containing protein of yet unknown function originally discovered in the sulfate reducers of the genus Desulfovibrio. It contains two iron-sulfur clusters: a cubane [4Fe-4S] and a mixed oxo- and sulfide-bridged 4Fe cluster of unprecedented structure. The recent determination of the genomic sequence of Escherichia coli (E. coli) has revealed a homologue of fuscoredoxin in this facultative microbe. The presence of this gene in E. coli raises interesting questions regarding the function of fuscoredoxin and whether this gene represents a structural homologue of the better-characterized Desulfovibrio proteins. In order to explore the latter, an overexpression system for the E. coli fuscoredoxin gene was devised. The gene was cloned from genomic DNA by use of the polymerase chain reaction into the expression vector pT7-7 and overexpressed in E. coli BL21(DE3) cells. After two chromatographic steps a good yield of recombinant protein was obtained (approximately 4 mg of pure protein per liter of culture). The purified protein exhibits an optical spectrum characteristic of the homologue from D. desulfuricans, indicating that cofactor assembly was accomplished. Iron analysis indicated that the protein contains circa 8 iron atoms/molecule which were shown by EPR and Mossbauer spectroscopies to be present as two multinuclear clusters, albeit with slightly altered spectroscopic features. A comparison of the primary sequences of fuscoredoxins is presented and differences on cluster coordination modes are discussed on the light of the spectroscopic data. (C) 1999 Academic Press.
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Chemosensors displaying pH controlled multistage fluorescence emission - Pina, F; Melo, MJ; Bernardo, M. A.; Luis, SV; Garcia-Espana, E (Journal of Photochemistry and Photobiology a-Chemistry, 1999)
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Times Cited: 20 Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; 20

Cloning and overexpression of E.Coli fuscoredoxin - Pamplona, A.; Pereira, A. S.; Tavares, P; Moura, I.; Rusnak, F.; Moura, J. J. G. (Journal Of Inorganic Biochemistry, 1999)
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Copper-containing nitrous oxide reductase from Pseudomonas nautica: spectroscopic and redox properties - Prudencio, M.; Pereira, A. S.; Tavares, P; Besson, S.; Moura, I. (Journal Of Inorganic Biochemistry, 1999)
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Cross immunological reactions and spectroscopy study within nitrate reductase and other mononuclear Mo containing enzymes of the sulfate reducing bacteria - Bursakov, S. A.; Brondino, C.; Dias, J. M.; Carneiro, C.; Caldeira, J.; Duarte, R. O.; Romao, M. J.; Moura, I.; Moura, J. J. G. (Journal of Inorganic Biochemistry, 1999)
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Times Cited: 0 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; 0

Crystal structure of the first dissimilatory nitrate reductase at 1.9 angstrom solved by MAD methods - Dias, J. M.; Than, M. E.; Humm, A.; Huber, R.; Bourenkov, G. P.; Bartunik, H. D.; Bursakov, S.; Calvete, J.; Caldeira, J.; Carneiro, C.; Moura, J. J. G.; Moura, I.; et al. (Structure with Folding & Design, 1999)
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Times Cited: 222 Romao, Maria/A-4115-2013; Moura, Jose/D-6426-2013; Szaleniec, Maciej/A-1198-2013; 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; 226

Crystallization and preliminary X-ray analysis of a nitrate reductase from Desulfovibrio desulfuricans ATCC 27774 - Dias, J. M.; Bursakov, S.; Carneiro, C.; Moura, J. J. G.; Moura, I.; Romao, M. J. (Acta Crystallographica Section D-Biological Crystallography, 1999)
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Times Cited: 4 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; 4

Crystallographic studies of a dissimilatory nitrate reductase and mechanistic implications - Dias, J. M.; Than, M. E.; Huber, R.; Bourenkov, G. P.; Bartunik, H. D.; Bursakov, S.; Moura, J. J. G.; Moura, I.; Romao, M. J. (Journal of Inorganic Biochemistry, 1999)
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Times Cited: 0 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; 0

Crystallographic studies on a tungsten-containning formate dehydrogenase from Desulfovibrio gigas - Teixeira, S.; Dias, J. M.; Carvalho, A. L.; Bourenkov, G.; Bartunik, H.; Almendra, M. J.; Moura, I.; Moura, J. J. G.; Romao, M. J. (Journal of Inorganic Biochemistry, 1999)
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Times Cited: 0 Romao, Maria/A-4115-2013; Carvalho, Ana Luisa/G-5638-2011; REQUIMTE, SMB/M-5694-2013; Moura, Isabel/D-6339-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; Carvalho, Ana Luisa/0000-0002-3824-0240; Moura, Isabel/0000-0003-0971-4977; 0

Effect of protonation and Zn(II) coordination on the fluorescence emission of a phenanthroline-containing macrocycle. An unusual case of "nonemissive'' Zn(II) complex - Bazzicalupi, C; Bencini, A; Bianchi, A; Giorgi, C; Fusi, V.; Valtancoli, B; Bernardo, M. A.; Pina, F (Inorganic Chemistry, 1999)
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Times Cited: 58 Pina, Fernando/C-8161-2011; Fusi, Vieri/H-1006-2012; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 58

Effects of protein-protein interactions on electron transfer: docking and electron transfer calculations for complexes between flavodoxin and c-type cytochromes - Cunha, C. A.; Romao, M. J.; Sadeghi, S. J.; Valetti, F.; Gilardi, G.; Soares, C.M. (Journal of Biological Inorganic Chemistry, 1999)
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Times Cited: 18 GILARDI, GIANFRANCO/B-4523-2010; Soares, Claudio/E-2675-2012; Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 19

Electrochemical studies on c-type cytochromes at microelectrodes - Correia dos Santos, M. M.; Paes de Sousa, P. M.; Simões Gonçalves, M. L.; Lopes, H.; Moura, I.; Moura, J. J. G. (Journal of Electroanalytical Chemistry, 1999)
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Keywords: Cytochrome c552; Cytochrome c553; Electrochemistry; Horse heart cytochrome c; Macro and microelectrodes

Macrocyclic polyamines containing phenanthroline moieties - Fluorescent chemosensors for H+ and Zn2+ ions - Bencini, A; Bernardo, M. A.; Bianchi, A; Fusi, V.; Giorgi, C; Pina, F; Valtancoli, B (European Journal of Inorganic Chemistry, 1999)
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Times Cited: 44 Pina, Fernando/C-8161-2011; Fusi, Vieri/H-1006-2012; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 45

Micelle effect on the 'write-lock-read-unlock-erase' cycle of 4 '-hydroxyflavylium ion - Roque, A.; Pina, F; Alves, S; Ballardini, R; Maestri, M; Balzani, V. (Journal of Materials Chemistry, 1999)
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Times Cited: 46 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 46

Photo- and pH-Induced transformations of flavylium cation: "Write-lock-read-unlock-erase" cycles - Pina, F; Melo, MJ; Maestri, M; Passaniti, P.; Camaioni, N.; Balzani, V. (European Journal of Organic Chemistry, 1999)
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Times Cited: 28 Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; Camaioni, Nadia/C-3790-2009; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; 28

Photochromic flavylium compounds as multistate/multifunction molecular-level systems - Pina, F; Maestri, M; Balzani, V. (Chemical Communications, 1999)
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Times Cited: 64 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 64

Photodegradation of acrylic resins used in the conservation of stone - Melo, MJ; Bracci, S.; Camaiti, M.; Chiantore, O.; Piacenti, F. (Polymer Degradation and Stability, 1999)
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Times Cited: 46 Melo, Maria Joao/C-8594-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; 52

Photophysical characteristics of two model antenna systems: a fucoxanthin-pyropheoporbide dyad and its peridinin analogue - Osuka, A; Kume, T; Haggquist, GW; Javorfi, T; J. C. Lima; Melo, E; Naqvi, KR (Chemical Physics Letters, 1999)
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Preliminary crystallographic studies of xanthine oxidase purified from rat liver - Romao, M. J.; Carvalho, A. L.; Dias, J. M.; Teixeira, S.; Bourenkov, G.; Bartunik, H.; Huber, R.; Maia, L.; Mira, L. (Journal of Inorganic Biochemistry, 1999)
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Times Cited: 0 Romao, Maria/A-4115-2013; Carvalho, Ana Luisa/G-5638-2011; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; Carvalho, Ana Luisa/0000-0002-3824-0240; 0

Probing the interface polarity of AOT reversed micelles using centro-symmetrical squaraine molecules - Laia, C. A. T.; Costa, S. M. B. (Physical Chemistry Chemical Physics, 1999)
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Times Cited: 18 Laia, Cesar/C-8651-2011; Costa, Silvia/H-7766-2012; REQUIMTE, PHOTO/M-4229-2013; Costa, Silvia/M-8085-2013; REQUIMTE, LAQV/N-9835-2013 Laia, Cesar/0000-0001-6410-6072; Costa, Silvia/0000-0002-6978-8903; 18

Product ion studies of some novel arylamine adducts of deoxyguanosine by matrix-assisted laser desorption/ionization and post-source decay - Chiarelli, MP; Wu, HP; Antunes, AM; Branco, P. S. (RAPID COMMUNICATIONS IN MASS SPECTROMETRY, 1999)
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Purification and characterization of a tungsten-containing formate dehydrogenase from Desulfovibrio gigas - Almendra, M. J.; Brondino, C. D.; Gavel, O.; Pereira, A. S.; Tavares, P; Bursakov, S.; Duarte, R.; Caldeira, J.; Moura, J. J. G.; Moura, I. (Biochemistry, 1999)
An air-stable formate dehydrogenase (FDH), an enzyme that catalyzes the oxidation of formate to carbon dioxide, was purified from the sulfate reducing organism Desulfovibrio gigas (D. gigas) NCIB 9332. D. gigas FDH is a heterodimeric protein [alpha (92 kDa) and beta (29 kDa) subunits] and contains 7 +/- 1 Fe/protein and 0.9 +/- 0.1 W/protein, Selenium was not detected. The UV/visible absorption spectrum of D, gigas FDH is typical of an iron-sulfur protein. Analysis of pterin nucleotides yielded a content of 1.3 +/- 0.1 guanine monophosphate/mol of enzyme, which suggests a tungsten coordination with two molybdopterin guanine dinucleotide cofactors. Both Mossbauer spectroscopy performed on D. gigas FDH grown in a medium enriched with Fe-57 and EPR studies performed in the native and fully reduced state of the protein confirmed the presence of two [4Fe-4S] clusters. Variable-temperature EPR studies showed the presence of two signals compatible with an atom in a d(1) configuration albeit with an unusual relaxation behavior as compared to the one generally observed for W(V) ions.
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Reactions of nitric oxide with the reduced non-heme diiron center of the soluble methane monooxygenase hydroxylase - Coufal, DE; Tavares, P; Pereira, A. S.; Hyunh, BH; Lippard, SJ (Biochemistry, 1999)
The soluble methane monooxygenase system from Methylococcus capsulatus (Bath) catalyzes the oxidation of methane to methanol and water utilizing dioxygen at a non-heme, carboxylate-bridged diiron center housed in the hydroxylase (H) component. To probe the nature of the reductive activation of dioxygen in this system, reactions of an analogous molecule, nitric oxide, with the diiron(II) form of the enzyme (H-red) Were investigated by both continuous and discontinuous kinetics methodologies using optical, EPR, and Mossbauer spectroscopy. Reaction of NO with H-red affords a dinitrosyl species, designated H-dinitrosyl, with optical spectra (lambda(max) = 450 and 620 nm) and Mossbauer parameters (delta = 0.72 mm/s, Delta E-Q = 1.55 mm/s) similar to those of synthetic dinitrosyl analogues and of the dinitrosyl adduct of the reduced ribonucleotide reductase R2 (RNR-R2) protein. The H-dinitrosyl species models features of the H-peroxo intermediate formed in the analogous dioxygen reaction. In the presence of protein B, H-dinitrosyl builds up with approximately the same rate constant as H-peroxo (similar to 26 s(-1)) at 4 degrees C. In the absence of protein B, the kinetics of H-dinitrosyl formation were best fit with a biphasic A --> B --> C model, indicating the presence of an intermediate species between H-red and H-dinitrosyl. This result contrasts with the reaction of H-red with dioxygen, in which the H-peroxo intermediate forms in measurable quantities only in the presence of protein B. These findings suggest that protein B may alter the positioning but not the availability of coordination sites on iron for exogenous ligand binding and reactivity.
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Redox potential of the heme protein KatG from Mycobacterium tuberculosis - Wengenack, N.; Lopes, H.; Kennedy, M.; Tavares, P; Pereira, A. S.; Moura, I.; Moura, J. J. G.; Rusnak, F. (Journal Of Inorganic Biochemistry, 1999)
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Selective lithium complexation by photoactive aza-cages bearing the anthracene function - Ciampolini, M.; Formica, M.; Fusi, V.; Saint-Mauricec, A.; Micheloni, M.; Nardi, N.; Pontellini, R.; Pina, F; Romani, P.; Sabatini, A. M.; Valtancoli, B (European Journal of Inorganic Chemistry, 1999)
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Times Cited: 6 Pina, Fernando/C-8161-2011; Fusi, Vieri/H-1006-2012; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 6

Simple and Complex Iron-Sulfur Proteins in Sulfate Reducing Bacteria - Moura, Isabel; Pereira, Alice S.; Tavares, Pedro; Moura, José J. G. (Advances in Inorganic Chemistry, 1999)
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Simple and complex iron-sulfur proteins in sulfate reducing bacteria - Moura, I.; Pereira, A. S.; Tavares, P; Moura, J. J. G. (1999)
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Spectroscopic characterization of porphyrin binding to ferrochelatase, the last enzyme in the heme biosynthetic pathway - Franco, R.; Ma, J. G.; Lu, Y.; Pereira, A.; Tavares, P; Moura, I.; Shelnutt, J. A.; Ferreira, G. C. (Journal Of Inorganic Biochemistry, 1999)
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Structural studies by X-ray diffraction on metal substituted desulforedoxin, a rubredoxin-type protein - Archer, M.; Carvalho, A. L.; Teixeira, S.; Moura, I.; Moura, J. J. G.; Rusnak, F.; Romao, M. J. (Protein Science, 1999)
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Times Cited: 12 Romao, Maria/A-4115-2013; Carvalho, Ana Luisa/G-5638-2011; REQUIMTE, SMB/M-5694-2013; Moura, Isabel/D-6339-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; Carvalho, Ana Luisa/0000-0002-3824-0240; Moura, Isabel/0000-0003-0971-4977; 13

Technical Systems, Organisation Forms and Social Implications: Statistical Analysis of the Firm Survey (Second Interim Report) - Schienstock, Gerd; Bechmann, Gotard; Flecker, Joerg; Huws, Ursula; Van Hootegem, Geert; Mirabile, Maria Luisa; António Moniz; Ò Siochru, Sean (University Library of Munich, Germany, 1999)
This is the second interim report of the research project "Information Society, Work and the Generation of New Forms of Social Exclusion" (SOWING). It is based on a firm survey conducted in the eight regions participating in the research project — Flanders (Belgium), Lazio (Italy), Niederösterreich (Austria), Portugal, the Republic of Ireland, the Stuttgart area (Germany), the Tampere region (Finland) and the West London area (U.K.). The aim of this report is to present a broad overview of the collected data. In general, only simple statistical methods have been applied. The report focuses on a regional comparison; however, the data have also been analysed by firm size, measured by quantity of staff, and industrial sector. It should be seen as a first step in the data analysis; it may also give some hints for a more strategic analysis of the survey data.
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Keywords: Information Society; Work

Thermodynamic and fluorescence emission studies on chemosensors containing anthracene fluorophores. Crystal structure of { (CuLCl)-Cl-1 Cl}(2)center dot 2H(2)O L-1 = N-(3-aminopropyl)-N '-3-(anthracen-9-ylmethyl)aminopropylethane-1,2-diamine - Bernardo, M. A.; Pina, F; Escuder, B.; Garcia-Espana, E; Godino-Salido, M. L.; Latorre, J.; Luis, SV; Ramirez, J. A.; Soriano, C (Journal of the Chemical Society-Dalton Transactions, 1999)
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Times Cited: 29 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 29

Thermodynamics and fluorescence emission studies on potential molecular chemosensors for ATP recognition in aqueous solution - Albelda, MT; Bernardo, M. A.; Garcia-Espana, E; Godino-Salido, M. L.; Luis, SV; Melo, MJ; Pina, F; Soriano, C (Journal of the Chemical Society-Perkin Transactions 2, 1999)
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Times Cited: 66 Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; Albelda, M. Teresa/J-5929-2012; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; 66

{Technical Systems, Organisation Forms and Social Implications: Statistical Analysis of the Firm Survey (Second Interim Report)} - Schienstock, Gerd; Bechmann, Gotard; Flecker, Joerg; Huws, Ursula; Van Hootegem, Geert; Mirabile, Maria Luisa; António Moniz; Ò Siochru, Sean (University Library of Munich, Germany, 1999)
This is the second interim report of the research project "Information Society, Work and the Generation of New Forms of Social Exclusion" (SOWING). It is based on a firm survey conducted in the eight regions participating in the research project — Flanders (Belgium), Lazio (Italy), Niederösterreich (Austria), Portugal, the Republic of Ireland, the Stuttgart area (Germany), the Tampere region (Finland) and the West London area (U.K.). The aim of this report is to present a broad overview of the collected data. In general, only simple statistical methods have been applied. The report focuses on a regional comparison; however, the data have also been analysed by firm size, measured by quantity of staff, and industrial sector. It should be seen as a first step in the data analysis; it may also give some hints for a more strategic analysis of the survey data.
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Keywords: Information Society; Work

The structural origin of nonplanar heme distortions in tetraheme ferricytochromes c3 - Ma, J. G.; Zhang, J.; Franco, R.; Jia, S. L.; Moura, I.; Moura, J. J.; Kroneck, P. M.; Shelnutt, J. A. (Biochemistry, 1998)
Resonance Raman (RR) spectroscopy, molecular mechanics (MM) calculations, and normal-coordinate structural decomposition (NSD) have been used to investigate the conformational differences in the hemes in ferricytochromes c3. NSD analyses of heme structures obtained from X-ray crystallography and MM calculations of heme-peptide fragments of the cytochromes c3 indicate that the nonplanarity of the hemes is largely controlled by a fingerprint peptide segment consisting of two heme-linked cysteines, the amino acids between the cysteines, and the proximal histidine ligand. Additional interactions between the heme and the distal histidine ligand and between the heme propionates and the protein also influence the heme conformation, but to a lesser extent than the fingerprint peptide segment. In addition, factors that influence the folding pattern of the fingerprint peptide segment may have an effect on the heme conformation. Large heme structural differences between the baculatum cytochromes c3 and the other proteins are uncovered by the NSD procedure [Jentzen, W., Ma, J.-G., and Shelnutt, J. A. (1998) Biophys. J. 74, 753-763]. These heme differences are mainly associated with the deletion of two residues in the covalently linked segment of hemes 4 for the baculatum proteins. Furthermore, some of these structural differences are reflected in the RR spectra. For example, the frequencies of the structure-sensitive lines (nu4, nu3, and nu2) in the high-frequency region of the RR spectra are lower for the Desulfomicrobium baculatum cytochromes c3 (Norway 4 and 9974) than for the Desulfovibrio (D.) gigas, D. vulgaris, and D. desulfuricans strains, consistent with a more ruffled heme. Spectral decompositions of the nu3 and nu10 lines allow the assignment of the sublines to individual hemes and show that ruffling, not saddling, is the dominant factor influencing the frequencies of the structure-sensitive Raman lines. The distinctive spectra of the baculatum strains investigated are a consequence of hemes 2 and 4 being more ruffled than is typical of the other proteins.
0006-2960 (Print)0006-2960 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Crystallography, X-Ray; Cytochrome c Group/*chemistry/metabolism; Desulfovibrio/chemistry; Heme/*chemistry/metabolism; Iron/metabolism; Models, Molecular; Oxidation-Reduction; Peptide Fragments/chemistry/metabolism; Porphyrins/chemistry/metabolism; Spectrum Analysis, Raman; Structure-Activity Relationship

Flexible molecules with defined shape. X. Synthesis and conformational study of 1,5-diaza-cis-decalin - Santos, AGD; W. Klute; J. Torode; V. P. W. Bohm; E. Cabrita; Runsink, J; Hoffmann, RW (New Journal of Chemistry, 1998)
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Fisheries Management: A new Challenge to Sociology - António Moniz (University Library of Munich, Germany, 1998)
As a Norwegian sociologist pointed out recently at the Encontro Internacional de Vilamoura on Fishing, “the fisheries management is the management of people, not fish" This statement may surprise many specialists, but it puts once again a series of questions and problems in their true place: society, social relationships, individuals. It is necessary to adopt a new attitude, a new type of intervention, a new vision, which may mean “community management”, a system of co-management, new models of business organisation and consumer behaviour. Towards this end, sociology can and should contribute with its analytical instruments, with its set of scientific reflections and controversies, to the enrichment of the knowledge about a complex reality in profound change, such as that of the socio-economic fisheries system.
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Keywords: business organisation; consumer behaviour; Fisheries; resources management; sociology

{Fisheries Management: A new Challenge to Sociology} - António Moniz (University Library of Munich, Germany, 1998)
As a Norwegian sociologist pointed out recently at the Encontro Internacional de Vilamoura on Fishing, “the fisheries management is the management of people, not fish" This statement may surprise many specialists, but it puts once again a series of questions and problems in their true place: society, social relationships, individuals. It is necessary to adopt a new attitude, a new type of intervention, a new vision, which may mean “community management”, a system of co-management, new models of business organisation and consumer behaviour. Towards this end, sociology can and should contribute with its analytical instruments, with its set of scientific reflections and controversies, to the enrichment of the knowledge about a complex reality in profound change, such as that of the socio-economic fisheries system.
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Keywords: business organisation; consumer behaviour; Fisheries; resources management; sociology

Oxovanadium(IV) complexes of the dipeptides glycyl-L-aspartic acid, L-aspartylglycine and related ligands; a spectroscopic and potentiometric study - Pessoa, J. C.; Gajda, T.; Gillard, R. D.; Kiss, T.; Luz, S. M.; Moura, J. J. G.; Tomaz, I.; Telo, J. P.; Torok, I. (Journal of the Chemical Society-Dalton Transactions, 1998)
The equilibria in the systems VO2+ + L (L = Gly-L-Asp, L-Asp-Gly, N-acetyl-L-aspartic acid or succinic acid) have been studied at 25 degrees C and 0.2 mol dm(3) K(CI) medium by a combination of potentiometric and spectroscopic methods (ESR, circular dichroism and visible absorption). Formation constants were calculated from pH-metric data with total oxovanadium(Iv) concentrations of(0.6-4) x 10(-3) mol dm(-3) and ligand-to-metal (L:M) ratios of 2-8 (AspGly) or 4-15: 1 (other systems). The position of the Asp residue in the peptide chain affects the co-ordination mode of the ligands: while in the GlyAsp system bis complexes start to form at pH less than 2, for AspGly only 1 : 1 complexes form, with relatively high CD signal. The co-ordination behaviour of N-acetyl-L-aspartic and succinic acids is similar. The results of potentiometric and spectroscopic methods are self consistent. Isomeric structures are discussed for each stoichiometry proposed and the results compared with those for L-aspartic acid and dipeptides with non-coordinating side chains.
Times Cited: 33

ATP sulfurylases from sulfate-reducing bacteria of the genus Desulfovibrio. A novel metalloprotein containing cobalt and zinc - Gavel, O. Y.; Bursakov, S. A.; Calvete, J. J.; George, G. N.; Moura, J. J.; Moura, I. (Biochemistry, 1998)
Adenosine triphosphate sulfurylase catalyzes the formation of adenosine 5'-phosphosulfate from adenosine triphosphate and sulfate. The enzyme plays a crucial role in sulfate activation, the key step for sulfate utilization, and has been purified from crude extracts of Desulfovibrio desulfuricans ATCC 27774 and Desulfovibrio gigas. Both proteins are homotrimers [141 kDa (3 x 47) for D. desulfuricans and 147 kDa (3 x 49) for D. gigas] and have been identified, for the first time, as metalloproteins containing cobalt and zinc. EXAFS reveals that either cobalt or zinc binds endogenously at presumably equivalent metal binding sites and is tetrahedrally coordinated to one nitrogen and three sulfur atoms. Furthermore, the electronic absorption spectra display charge-transfer bands at 335 and 370 nm consistent with sulfur coordination to cobalt, and as expected for a distorted tetrahedral cobalt geometry, d-d bands are observed at 625, 666, and 715 nm. This geometry is supported by the observation of high-spin Co2+ EPR signals at g approximately 6.5.
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: Amino Acid Sequence; Binding Sites; Cobalt/*chemistry/metabolism; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Metalloproteins/*chemistry/metabolism; Molecular Sequence Data; Oxidation-Reduction; Spectrophotometry, Ultraviolet; Spectrum Analysis; Sulfate Adenylyltransferase/*chemistry/isolation & purification/metabolism; Sulfates/chemistry; X-Rays; Zinc/*chemistry/metabolism

A pterocarpan from Ulex parviflorus - Maximo, P; Lourenco, A. (PHYTOCHEMISTRY, 1998)
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Spectroscopic characterization of a novel tetranuclear Fe cluster in an iron-sulfur protein isolated from Desulfovibrio desulfuricans - Tavares, P; Pereira, A. S.; Krebs, C.; Ravi, N.; Moura, J. J.; Moura, I.; Huynh, B. H. (Biochemistry, 1998)
Mossbauer and EPR spectroscopies were used to characterize the Fe clusters in an Fe-S protein isolated from Desulfovibrio desulfuricans (ATCC 27774). This protein was previously thought to contain hexanuclear Fe clusters, but a recent X-ray crystallographic measurement on a similar protein isolated from Desulfovibrio vulgaris showed that the protein contains two tetranuclear clusters, a cubane-type [4Fe-4S] cluster and a mixed-ligand cluster of novel structure [Lindley et al. (1997) Abstract, Chemistry of Metals in Biological Systems, European Research Conference, Tomar, Portugal]. Three protein samples poised at different redox potentials (as-purified, 40 and 320 mV) were investigated. In all three samples, the [4Fe-4S] cluster was found to be present in the diamagnetic 2+ oxidation state and exhibited typical Mossbauer spectra. The novel-structure cluster was found to be redox active. In the 320-mV and as-purified samples, the cluster is at a redox equilibrium between its fully oxidized and one-electron reduced states. In the 40-mV sample, the cluster is in a two-electron reduced state. Distinct spectral components associated with the four Fe sites of cluster 2 in the three oxidation states were identified. The spectroscopic parameters obtained for the Fe sites reflect different ligand environments, making it possible to assign the spectral components to individual Fe sites. In the fully oxidized state, all four iron ions are high-spin ferric and antiferromagnetically coupled to form a diamagnetic S = 0 state. In the one-electron and two-electron reduced states, the reducing electrons were found to localize, consecutively, onto two Fe sites that are rich in oxygen/nitrogen ligands. Based on the X-ray structure and the Mossbauer parameters, attempts could be made to identify the reduced Fe sites. For the two-electron reduced cluster, EPR and Mossbauer data indicate that the cluster is paramagnetic with a nonzero interger spin. For the one-electron reduced cluster, the data suggest a half-integer spin of 9/2. Characteristic fine and hyperfine parameters for all four Fe sites were obtained. Structural implications and the nature of the spin-coupling interactions are discussed.
0006-2960 (Print)0006-2960 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Bacterial Proteins; Desulfovibrio/*chemistry; Electron Spin Resonance Spectroscopy; Iron-Sulfur Proteins/*chemistry/isolation & purification; Spectroscopy, Mossbauer

Iron compounds after erythrophagocytosis: chemical characterization and immunomodulatory effects - Costa, L. M.; Moura, E. M.; Moura, J. J.; de Sousa, M. (Biochem Biophys Res Commun, 1998)
In humans, the lymphomyeloid system has a fundamental role on iron metabolism promoting its recycling due to a continuous removal of effete red blood cells. Additionally, one of the most intriguing aspects of metalloporphyrins in biology is their effect on the immune system. However, the process of erythrocyte catabolism is still poorly understood and needs further research. In the present study, we attempt to investigate the nature and the possible physiologic role of Fe compounds released after erythrophagocytosis during the removal of red blood cells. Monocyte erythrophagocytosis in vitro experiments were done to characterize chemically the Fe compounds present inside the cells and in the culture supernatants. We tested the probable immunomodulatory functions of erythrophagocytosis products over lymphocyte cultures activated in vitro with T mitogens (alpha-CD3). Data obtained from atomic absorption spectroscopy confirmed the presence of Fe in the culture supernatants of monocyte cultures after erythrophagocytosis. Also, high-spin haem complexes derived from erythrocyte catabolism were detected by electron paramagnetic electronic resonance. Finally, in vitro activated lymphocyte proliferation experiments indicate the co-mitogenic properties of monocyte culture supernatants after red blood cells phagocytosis. Thus, the results of the present work provide evidence that culture monocyte supernatants after in vitro erythrophagocytosis contain Fe (III) high-spin haem complexes and show lymphocyte proliferation co-stimulatory properties.
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: *Phagocytosis; Adjuvants, Immunologic/blood/chemistry/*physiology; Antibodies, Monoclonal/pharmacology; Antigens, CD3/immunology; Cell-Free System/immunology; Cells, Cultured; Electron Spin Resonance Spectroscopy; Erythrocytes/*chemistry/immunology; Humans; Interleukin-1/analysis/physiology; Iron Compounds/*blood/*chemistry/pharmacology; Lymphocyte Activation/drug effects/immunology; Monocytes/chemistry/immunology; Spectrophotometry, Atomic; Tumor Necrosis Factor-alpha/analysis/physiology

Bacterial contig map of the 21q11 region associated with Alzheimer's disease and abnormal myelopoiesis in Down syndrome - GROET, J; Ives, J. H.; South, A. P.; Baptista, P. R.; Jones, T. A.; Yaspo, M. L.; H. Lehrach; Potier, M. C.; Van Broeckhoven, C.; Nizetic, D (Genome Research, 1998)
We present a high-resolution bacterial contig map of 3.4 Mb of genomic DNA in human chromosome 21q11-q21, encompassing the region of elevated disomic homozygosity in Down Syndrome-associated abnormal myelopoiesis and leukemia, as well as the markers, which has shown a strong association with Alzheimer's Disease that has never been explained. The map contains 89 overlapping PACs, BACs, or cosmids in three contigs (850, 850, and 1500 kb) with two gaps (one of 140-210 kb and the second < 5 kb). To date, eight transcribed sequences derived by cDNA selection, exon trapping, and/or global EST sequencing have been positioned onto the map, and the only two genes so far mapped to this cytogenetic region, STCH and RIP140 have been precisely localized. This work converts a further 10% of chromosome 21q into a high-resolution bacterial contig map, which will be the physical basis for the long-range sequencing of this region. The map will also enable positional derivation of new transcribed sequences, as well as new polymorphic probes, that will help in elucidation of the role the genes in this region may play in abnormal myelopoiesis and leukemia associated with trisomy 21 and Alzheimer's Disease.
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Keywords: complementary DNA; contig; DNA; DNA marker

Construction of a YAC/PAC physical map of a gene rich region in 1p13.3. - Baptista, Pedro Miguel Ribeiro Viana (European Journal of Human Genetics, 1998)
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Construction and analysis of a sequence-ready map in 4q25: Rieger syndrome can be caused by haploinsufficiency of RIEG, but also by chromosome breaks approximate to 90 kb upstream of this gene - Flomen, Rachel H.; Vatcheva, Radost; Gorman, Patricia A.; Baptista, Pedro Miguel Ribeiro Viana; Groet, Jürgen (Genomics, 1998)
The autosomal dominant disorder Rieger syndrome (RIEG) shows genetic heterogeneity and has a phenotype characterized by malformations of the anterior segment of the eye, failure of the periumbilical skin to involute, and dental hypoplasia. The main locus for RIEG was mapped to the 4q25-q27 chromosomal segment using a series of cytogenetic abnormalities as well as by genetic linkage to DNA markers. Recently, a bicoid-related homeobox transcription factor gene called RIEG has been cloned, characterized, and proven to cause the 4q25 linked RIEG. Its mode of action in the pathogenesis of RIEG was not conclusively proven, since most etiological mutations detected. In the RIEG sequence caused amino acid substitutions or splice changes in the homeodomain. Through FISH analysis of a 460-kb sequence-ready map (PAC contig) around RIEG that we report in this paper, we demonstrate that the 4q25 linked RIEG disorder can arise from the haploid, whole-gene deletion of RIEG, but also from a translocation break 90 kb upstream from the gene. The data provide conclusive evidence that physical or functional haploinsufficiency of RIEG is the pathogenic mechanism for Rieger syndrome. The map also defines restriction fragments bearing sequences with a potential key regulatory role in the control of homeobox gene expression.
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The surface-charge asymmetry and dimerisation of cytochrome c550 from Paracoccus denitrificans--implications for the interaction with cytochrome c peroxidase - Pettigrew, G. W.; Gilmour, R.; Goodhew, C. F.; Hunter, D. J.; Devreese, B.; Van Beeumen, J.; Costa, C.; Prazeres, S.; Krippahl, L.; Palma, P. N.; Moura, I.; Moura, J. J. (Eur J Biochem, 1998)
The implications of the dimeric state of cytochrome c550 for its binding to Paracoccus cytochrome c peroxidase and its delivery of the two electrons required to restore the active enzyme during catalysis have been investigated. The amino acid sequence of cytochrome c550 of Paracoccus denitrificans strain LMD 52.44 was determined and showed 21 differences from that of strain LMD 22.21. Based on the X-ray structure of the latter, a structure for the cytochrome c550 monomer from strain 52.44 is proposed and a dipole moment of 945 debye was calculated with an orientation close to the exposed haem edge. The behaviour of the cytochrome on molecular-exclusion chromatography is indicative of an ionic strength-dependent monomer (15 kDa)/dimer (30 kDa) equilibrium that can also be detected by 1H-NMR spectroscopy. The apparent mass of 50 kDa observed at very low ionic strength was consistent with the presence of a strongly asymmetric dimer. This was confirmed by cross-linking studies, which showed that a cross-linked species of mass 30 kDa on SDS behaved with an apparent mass of 50 kDa on molecular-exclusion chromatography. A programme which carried out and evaluated molecular docking of two monomers to give a dimer generated a most probable dimer in which the monomer dipoles lay almost antiparallel to each other. The resultant dipole moment of the dimer is therefore small. Although this finding calls into question the possibility of preorientation of a strongly asymmetrically charged cytochrome as it collides with a redox partner, the stoichiometry of complex formation with cytochrome c peroxidase as studied by 1H-NMR spectroscopy shows that it is the monomer that binds.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Amino Acid Sequence; Bacterial Proteins/chemistry; Carbodiimides/metabolism; Computer Simulation; Cross-Linking Reagents/metabolism; Cytochrome c Group/*chemistry; Cytochrome-c Peroxidase/*metabolism; Dimerization; Electron Transport/physiology; Kinetics; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Sequence Data; Osmolar Concentration; Oxidation-Reduction; Paracoccus denitrificans/*chemistry; Protein Binding; Sequence Analysis

Electrochemical study on cytochrome c peroxidase from Paracoccus denitrificans: a shifting pattern of structural and thermodynamic properties as the enzyme is activated - Lopes, H.; Pettigrew, G. W.; Moura, I.; Moura, J. J. G. (Journal of Biological Inorganic Chemistry, 1998)
The di-haem cytochrome c peroxidase of Paracoccus denitrificans is a calcium binding dimer of 37.5 kDa subunits. It is responsible for reduction of H(2)O(2) to H(2)O with oxidation of cytochrome c(550) and is isolated in a fully oxidised state (inactive) in which one haem (centre I) is in a high-spin/low-spin equilibrium and high potential and the other (centre II) is low-spin and low potential. The enzyme undergoes direct electron transfer (without the need for mediators) with a 4,4'-dithiodipyridine-modified gold electrode and the response of both haem groups can be observed. By combination of the cyclic and pulse voltammetric data with the established spectroscopic information, it was demonstrated that entry of one electron to the high potential haem leads (in a mechanism involving strong haem-haem interactions) to a complex change of spin states and redox potentials of both haems in order to attain a "ready state" for binding, reduction and cleavage of the hydrogen peroxide. In the absence of endogenous calcium, haem communication can be completely disconnected and is recovered only when Ca(2+) is added, an essential step for the formation of the peroxidatic site. The intricate electrochemical behaviour of this enzyme was interpreted as a mechanism involving, both reduction and oxidation of the high potential haem, an interfacial electron transfer coupled to a homogenous chemical reaction (EC mechanism). We discuss two different models for the sequence of events leading to the appearance of the active pentacoordinated peroxidatic haem.
Times Cited: 13

Metal binding to the tetrathiolate motif of desulforedoxin and related polypeptides - Kennedy, M.; Yu, L.; Lima, M. J.; Ascenso, C. S.; Czaja, C.; Moura, I.; Moura, J. J. G.; Rusnak, F. (Journal of Biological Inorganic Chemistry, 1998)
Desulforedoxin and the N-terminus of desulfoferrodoxin share a 36 amino acid domain containing a (Cys-S)(4) metal binding site. Recombinant forms of desulforedoxin, an N-terminal fragment of desulfoferrodoxin, and two desulforedoxin mutant proteins were reconstituted with Fe3+ Cd2+, and Zn2+ and relative metal ion affinities assessed by proton titrations. Protons compete with metal for protein ligands, a process that can be followed by monitoring the optical spectrum of the metal-protein complex as a function of pH. For all polypeptides, Fe3+ bound with the highest affinity, whereas the affinity of Zn2+ was greater than Cd2+ in desulforedoxin and the N-terminal fragment of desulfoferrodoxin, but this order was reversed in desulforedoxin mutant proteins. Metal binding in both mutants was significantly impaired. Furthermore, the Fe3+ complex of both mutants underwent a time-dependent bleaching process which coincided with increased reactivity of cysteine residues to Ellman's reagent and concomitant metal dissociation. It is hypothesized that this results from an autoredox reaction in which Fe3+ is reduced to Fe2+ with attendant oxidation of ligand thiols.
Times Cited: 6

Isolation and characterisation of a novel sulphate-reducing bacterium of the Desulfovibrio genus - Feio, M. J.; Beech, I. B.; Carepo, M.; Lopes, J. M.; Cheung, C. W.; Franco, R.; Guezennec, J.; Smith, J. R.; Mitchell, J. I.; Moura, J. J.; Lino, A. R. (Anaerobe, 1998)
A novel sulphate-reducing bacterium (Ind 1) was isolated from a biofilm removed from a severely corroded carbon steel structure in a marine environment. Light microscopy observations revealed that cells were Gram-negative, rod shaped and very motile. Partial 16S rRNA gene sequencing and analysis of the fatty acid profile demonstrated a strong similarity between the new species and members from the Desulfovibrio genus. This was confirmed by the results obtained following purification and characterisation of the key proteins involved in the sulphate-reduction pathway. Several metal-containing proteins, such as two periplasmic proteins: hydrogenase and cytochrome c3, and two cytoplasmic proteins: ferredoxin and sulphite reductase, were isolated and purified. The latter proved to be of the desulfoviridin type which is typical of the Desulfovibrio genus. The study of the remaining proteins revealed a high degree of similarity with the homologous proteins isolated from Desulfovibrio gigas. However, the position of the strain within the phylogenetic tree clearly indicates that the bacterium is closely related to Desulfovibrio gabonensis, and these three strains form a separate cluster in the delta subdivision of the Proteobacteria. On the basis of the results obtained, it is suggested that Ind 1 belongs to a new species of the genus Desulfovibrio, and the name Desulfovibrio indonensis is proposed.
1075-9964 (Print)1075-9964 (Linking)Journal Article

NMR determination of the global structure of the 113Cd derivative of desulforedoxin: investigation of the hydrogen bonding pattern at the metal center - Goodfellow, B. J.; Rusnak, F.; Moura, I.; Domke, T.; Moura, J. J. (Protein Sci, 1998)
Desulforedoxin (Dx) is a simple homodimeric protein isolated from Desulfovibrio gigas (Dg) containing a distorted rubredoxin-like center with one iron coordinated by four cysteinyl residues (7.9 kDa with 36 amino acids per monomer). In order to probe the geometry and the H-bonding at the active site of Dx, the protein was reconstituted with 113Cd and the solution structure determined using 2D NMR methods. The structure of this derivative was initially compared with the NMR solution structure of the Zn form (Goodfellow BJ et al., 1996, J Biol Inorg Chem 1:341-353). Backbone amide protons for G4, D5, G13, L11 NH, and the Q14 NH side-chain protons, H-bonded in the X-ray structure, were readily exchanged with solvent. Chemical shift differences observed for amide protons near the metal center confirm the H-bonding pattern seen in the X-ray model (Archer M et al., 1995, J Mol Biol 251:690-702) and also suggest that H-bond lengths may vary between the Fe, Zn, and 113Cd forms. The H-bonding pattern was further probed using a heteronuclear spin echo difference (HSED) experiment; the results confirm the presence of NH-S H-bonds inferred from D2O exchange data and observed in the NMR family of structures. The presence of "H-bond mediated" coupling in Dx indicates that the NH-S H-bonds at the metal center have significant covalent character. The HSED experiment also identified an intermonomer "through space" coupling for one of the L26 methyl groups, indicating its proximity to the 113Cd center in the opposing monomer. This is the first example of an intermonomer "through space" coupling. Initial structure calculations produced subsets of NMR families with the S of C28 pointing away from or toward the L26 methyl: only the subset with the C28 sulfur pointing toward the L26 methyl could result in a "through space" coupling. The HSED result was therefore included in the structure calculations. Comparison of the Fe, Zn, and 113Cd forms of Dx suggests that the geometry of the metal center and the global fold of the protein does not vary to any great extent, although the H-bond network varies slightly when Cd is introduced. The similarity between the H-bonding pattern seen at the metal center in Dx, Rd (including H-bonded and through space-mediated coupling), and many zinc-finger proteins suggests that these H-bonds are structurally vital for stabilization of the metal centers in these proteins.
0961-8368 (Print)0961-8368 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: *Hydrogen Bonding; Amino Acid Sequence; Binding Sites/physiology; Cadmium/*chemistry; Crystallography, X-Ray; Desulfovibrio/*chemistry; Dimerization; Iron-Sulfur Proteins/*chemistry; Magnetic Resonance Spectroscopy; Metalloproteins/chemistry; Models, Molecular; Molecular Sequence Data

Modulation of the ligational properties of a new cylindrical macrotricycle by coupling of photochemical- and pH-switching properties - Bencini, A; Bernardo, M. A.; Bianchi, A; Ciampolini, M.; Fusi, V.; Nardi, N.; A. J. Parola; Pina, F; Valtancoli, B (Journal of the Chemical Society-Perkin Transactions 2, 1998)
The new cylindrical molecule L containing two tetraazamacrocyclic rings linked by two azobenzene pillars displays photoelastic properties, Light absorption at 366 nm gives rise to trans --> cis isomerization of the azobenzene moieties producing two isomers containing one or two cis-azobenzenes, respectively, The three trans-trans (E-E), trans-cis (E-Z) and cis-cis (Z-Z) isomers have been identified and characterized by H-1 NMR spectroscopy, allowing the dependence of their formation percentages with irradiation time to be determined, The sequence of photochemical reactions E-E --> E-Z --> Z-Z allows almost complete conversion of the E-E into the Z-Z isomer at 366 nm and 298 K, Both thermal (k = 1.75 x 10(-5) s(-1) at 313 K) and photo-induced (at 436 and 313 nm) back-isomerization reactions have been studied, The protonation constants of the three isomers in equimolar solutions of water-DMSO indicate a decreasing basicity in the order E-E > E-Z > Z-Z, in agreement with increasing electrostatic repulsion between the positive charges caused by a reduction in the separation between the protonation sites occurring upon Z --> E isomerization.
ISI Document Delivery No.: YY098Times Cited: 14 Cited Reference Count: 24 Bencini, A Bernardo, MA Bianchi, A Ciampolini, M Fusi, V Nardi, N Parola, AJ Pina, F Valtancoli, B Pina, Fernando/C-8161-2011; Fusi, Vieri/H-1006-2012; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Royal soc chemistry Cambridge

pH-controlled photochromism of hydroxyflavylium ions - Pina, F; Melo, MJ; A. J. Parola; Maestri, M; Balzani, V. (Chemistry-a European Journal, 1998)
The structural transformations and photochromic properties of the 7-hydroxyflavylium ion have been investigated by means of the pH jump technique and continuous and pulsed light excitation. The primary photoproduct of UV irradiation of the colorless trans-chalcone form, which is the predominant species at pH 4, is its colorless cis isomer, which rapidly disappears on a time scale of seconds through two competitive processes: i) back-reaction to yield the trans-chalcone form, and ii) formation of the colored flavylium ion and its conjugated quinoidal base. Over minutes or hours (depending on pH), the system reverts quantitatively to its original state. The rate constants and equilibrium constants of the various processes have been obtained and compared with those previously reported for the 4'-hydroxyflavylium and 4',7-dihydroxyflavylium ions. This comparison demonstrates the substituent effect on the rate and equilibrium constants; the effect on the rate constant of the cis-->trans thermal isomerization reaction is particularly strong. For the 7-hydroxyflavylium and 4',7-dihydroxyflavylium ions the pH of the solution plays the role of a tap for the color intensity generated by light excitation. This also means that this system can be viewed as a light-switchable pH indicator.
ISI Document Delivery No.: 128DKTimes Cited: 37 Cited Reference Count: 21 Pina, F Melo, MJ Parola, AJ Maestri, M Balzani, V Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Wiley-v c h verlag gmbh Berlin

Supramolecular interactions between Co(CN)(5)(SO3)(4-) and polyammonium macrocyclic receptors - A. J. Parola; Pina, F; Manfrin, M. F.; Moggi, L. (Journal of the Chemical Society-Dalton Transactions, 1998)
The acid-base properties as well as the photochemical reactivity of the co-ordination compound K-4[Co(CN)(5)(SO3)] in the presence of three polyammonium macrocyclic receptors were studied in aqueous solution. The pK(a) of the free complex (3.9) (sulfite deprotonation) changed to pK(a) <0.5 upon complexation with the receptors. The quantum yield for sulfite photoaquation of the free complex in the basic form (Phi = 0.85 +/- 0.09) decreased to 0.05 +/- 0.01, 0.12 +/- 0.03 and 0.45 +/- 0.09 in the presence of[24]aneN(8)H(8)(8+), [30]aneN(10)H(10)(10+) and [32]aneN(8)H(8)(8+), respectively. For the acidic form of the free complex (Phi = 0.40 +/- 0.05) the quantum yield was not affected by supercomplexation with [32]aneN(8)H(8)(8+). For the adducts formed from the other two macrocyclic receptors it was not possible to evaluate the quantum yields of the acidic forms, because protonation was not complete even at very high proton concentrations. The results were interpreted in terms of second-sphere interactions involving hydrogen bonding between the complex and the macrocycles. In the case of [32]aneN(8)H(8)(8+) the experimental results are compatible with a structure in which the cyanides are involved in hydrogen bonding but the sulfite ligand is not. In the two other supercomplexes the sulfite ligand seems to be involved in hydrogen bonding.
ISI Document Delivery No.: ZE272Times Cited: 5 Cited Reference Count: 36 Parola, AJ Pina, F Manfrin, MF Moggi, L Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Royal soc chemistry Cambridge

Synthesis and characterization of binuclear transition metal rhenium(VII) complexes with bridging cyanide ligands - Goncalves, I. S.; Kuhn, F. E.; Lopes, A. D.; A. J. Parola; Pina, F; J. Sotomayor; Romao, C. C. (Journal of Organometallic Chemistry, 1998)
Reacting transition metal complexes in low oxidation states, containing one or two cyanide ligands, with methyltrioxorhenium(VII) leads to bridged mixed metal compounds in good yields. The Re(VII) core is then surrounded by five or six ligands, respectively. The strength of these CN bridges and thus the stability of the newly generated bimetallic compound strongly depends on the donor strength of the ligands surrounding of the Cr/Mo/W or Fe moiety. The stability of the mixed metal molecules is reflected in the temperature dependent behavior of their O-17-NMR spectra, in their IR (Re=O) stretching frequencies and force constants, as well as several other spectroscopic data. UV-vis absorption spectra show the appearance of charge transfer bands. In the case of the mixed Mo/Re complexes the Mo-95-NMR spectroscopy is also a helpful tool to examine the donor capability of the Mo moiety. The described compounds also show photosensitivity. (C) 1998 Elsevier Science S.A. All rights reserved.
ISI Document Delivery No.: ZY869Times Cited: 9 Cited Reference Count: 36 Goncalves, IS Kuhn, FE Lopes, AD Parola, AJ Pina, F Sotomayor, J Romao, CC Pina, Fernando/C-8161-2011; Lopes, Andre/E-2136-2012; Romao, Carlos /D-1162-2010; Kuhn, Fritz/A-3113-2010; Parola, A. Jorge/F-4048-2010; Sotomayor, Joao/D-8103-2013; Goncalves, Isabel/H-3742-2013 Romao, Carlos /0000-0001-5061-3743; Parola, A. Jorge/0000-0002-1333-9076; Sotomayor, Joao/0000-0002-4589-0591; Elsevier science sa Lausanne

Molecular Basis for Energy Transduction: Mechanisms of Cooperativity in Multihaem Cytochromes - Louro, R.O.; Catarino, T.; Salgueiro, C.A.; Legall, J.; Turner, D.L.; Xavier, A. V. (Biological Electron Transfer Chains: Genetics, Composition and Mode of Operation NATO ASI Series Volume 512, 1998)
Energy transduction through electron/proton cooperativity is at the heart of the metabolism of every living organism Nonetheless, the search for the structural bases sustaining these phenomena has been hindered by the fact that they are usually associated with complex transmembrane proteins of high molecular weight.

Replacement of Lysine 45 by Uncharged Residues Modulates the Redox-Bohr Effect in Tetraheme Cytochrome c3 of Desulfovibrio vulgaris (Hildenborough) - Saraiva, Lígia M.; Salgueiro, C.A.; da Costa, Patrícia N.; Ana C. Messias; Legall, Jean; van Dongen, Walter M. A. M.; Xavier, António V. (Biochemistry, 1998)
The structural basis for the pH dependence of the redox potential in the tetrahemic Desulfovibrio vulgaris (Hildenborough) cytochrome c3 was investigated by site-directed mutagenesis of charged residues in the vicinity of heme I. Mutation of lysine 45, located in the neighborhood of the propionates of heme I, by uncharged residues, namely threonine, glutamine and leucine, was performed. The replacement of a conserved charged residue, aspartate 7, present in the N-terminal region and near heme I was also attempted. The analysis of the redox interactions as well as the redox-Bohr behavior of the mutated cytochromes c3 allowed the conclusion that residue 45 has a functional role in the control of the pKa of the propionate groups of heme I and confirms the involvement of this residue in the redox-Bohr effect.

A Sustentabilidade no Processo de Planeamento - Amado, Miguel (Geologia e Geotecnia no Planeamento e Gestão Urbana, 1998)

Altered specificity mutations define residues essential for substrate positioning in xanthine dehydrogenase - Glatigny, A.; Hof, P.; Romao, M. J.; Huber, R.; Scazzocchio, C. (Journal of Molecular Biology, 1998)
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Times Cited: 20 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 22

Caffeine interaction with synthetic flavylium salts. A flash photolysis study for the adduct involving 4 ',7-dihydroxyflavylium - Pina, F (Journal of Photochemistry and Photobiology a-Chemistry, 1998)
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Times Cited: 6 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 6

Color stabilization of malvidin 3-glucoside: Self-aggregation of the flavylium cation and copigmentation with the Z-chalcone form - Houbiers, C; J. C. Lima; Macanita, AL; Santos, H. (Journal of Physical Chemistry B, 1998)
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Direct spectroscopic and kinetic evidence for the involvement of a peroxodiferric intermediate during the ferroxidase reaction in fast ferritin mineralization - Pereira, A. S.; Small, W; Krebs, C.; Tavares, P; Edmondson, D. E.; Theil, EC; Huynh, B. H. (Biochemistry, 1998)
Rapid freeze-quench (RFQ) Mossbauer and stopped-flow absorption spectroscopy were used to monitor the ferritin ferroxidase reaction using recombinant (apo) frog M ferritin; the initial transient ferric species could be trapped by the RFQ method using low iron loading (36 Fe2+/ferritin molecule). Biphasic kinetics of ferroxidation were observed and measured directly by the Mossbauer method; a majority (85%) of the ferrous ions was oxidized at a fast rate of similar to 80 s(-1) and the remainder at a much slower rate of similar to 1.7 s(-1). In parallel with the fast phase oxidation of the Fe2+ ions, a single transient iron species is formed which exhibits magnetic properties (diamagnetic ground state) and Mossbauer parameters (Delta E-Q = 1.08 +/- 0.03 mm/s and delta = 0.62 +/- 0.02 mm/s) indicative of an antiferromagnetically coupled peroxodiferric complex. The formation and decay rates of this transient diiron species measured by the RFQ Mossbauer method match those of a transient blue species (lambda(max) = 650 nm) determined by the stopped-flow absorbance measurement. Thus, the transient colored species is assigned to the same peroxodiferric intermediate. Similar transient colored species have been detected by other investigators in several other fast ferritins (H and M subunit types), such as the human H ferritin and the Escherichia coli ferritin, suggesting a similar mechanism for the ferritin ferroxidase step in all fast ferritins. Peroxodiferric complexes are also formed as early intermediates in the reaction of O-2 With the catalytic diiron centers in the hydroxylase component of soluble methane monooxygenase (MMOH) and in the D84E mutant of the R2 subunit of E. coli ribonucleotide reductase. The proposal that a single protein site, with a structure homologous to the diiron centers in MMOH and R2, is involved in the ferritin ferroxidation step is confirmed by the observed kinetics, spectroscopic properties, and purity of the initial peroxodiferric species formed in the frog M ferritin.
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Dynamic light scattering study of AOT microemulsions with nonaqueous polar additives in an oil continuous phase - Laia, C. A. T.; Lopez-Cornejo, P.; Costa, S. M. B.; d'Oliveira, J.; Martinho, J. M. G. (Langmuir, 1998)
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Times Cited: 61 Laia, Cesar/C-8651-2011; Costa, Silvia/H-7766-2012; REQUIMTE, PHOTO/M-4229-2013; Costa, Silvia/M-8085-2013; REQUIMTE, LAQV/N-9835-2013; Martinho, Jose/E-1988-2013 Laia, Cesar/0000-0001-6410-6072; Costa, Silvia/0000-0002-6978-8903; Martinho, Jose/0000-0003-1806-1568 62

Excited state proton transfer in synthetic flavylium salts: 4-methyl-7-hydroxyflavylium and 4 ',7-dihydroxyflavylium - Example of a four-level molecular device to invert the population of the excited state - Pina, F; Melo, MJ; Santos, H.; J. C. Lima; Abreu, I; Ballardini, R; Maestri, M (New Journal of Chemistry, 1998)
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Fluorescence quenching of a squaraine dye by water in AOT reversed micelles - Laia, C. A. T.; Costa, S. M. B. (Journal of the Chemical Society-Faraday Transactions, 1998)
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Times Cited: 25 Laia, Cesar/C-8651-2011; Costa, Silvia/H-7766-2012; REQUIMTE, PHOTO/M-4229-2013; Costa, Silvia/M-8085-2013; REQUIMTE, LAQV/N-9835-2013 Laia, Cesar/0000-0001-6410-6072; Costa, Silvia/0000-0002-6978-8903; 25

Generation of a mixed-valent Fe(III)Fe(IV) form of intermediate Q in the reaction cycle of soluble methane monooxygenase, an analog of intermediate X in ribonucleotide reductase R2 assembly - Valentine, AM; Tavares, P; Pereira, A. S.; Davydov, R; Krebs, C.; Koffman, BM; Edmondson, D. E.; Huynh, B. H.; Lippard, SJ (Journal Of The American Chemical Society, 1998)
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Ground- and excited-state solvation of a squaraine dye by water in dioxane - Laia, C. A. T.; Costa, S. M. B. (Chemical Physics Letters, 1998)
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Times Cited: 11 Laia, Cesar/C-8651-2011; Costa, Silvia/H-7766-2012; REQUIMTE, PHOTO/M-4229-2013; Costa, Silvia/M-8085-2013; REQUIMTE, LAQV/N-9835-2013 Laia, Cesar/0000-0001-6410-6072; Costa, Silvia/0000-0002-6978-8903; 11

Ion-pairing co-pigmentation with 4 ',7-dihydroxyflavylium studied by pulse light jumps - Pina, F; Roque, A. (Journal of Photochemistry and Photobiology a-Chemistry, 1998)
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Times Cited: 2 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 2

Kinetics of ultra-fast excited state proton transfer from 7-hydroxy-4-methylflavylium chloride to water - J. C. Lima; Abreu, I; Brouillard, R; Macanita, AL (Chemical Physics Letters, 1998)
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Multislate/multifunctional molecular-level systems: Light and pH switching between the various forms of a synthetic flavylium salt - Pina, F; Roque, A.; Melo, MJ; Maestri, I.; Belladelli, L.; Balzani, V. (Chemistry-a European Journal, 1998)
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Times Cited: 90 Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; 90

Non-diffusion-controlled excimer formation with indane and acenaphthene. Kinetics and thermodynamics from picosecond-time-resolved fluorescence - Vigil, MR; Renamayor, CS; Pierola, I; J. C. Lima; Melo, EC; Macanita, AL (Chemical Physics Letters, 1998)
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Probing the iron environment in desulforedoxin. EXAFS of oxidized and reduced states - Stalhandske, CMV; Dong, J.; Tavares, P; Liu, M. Y.; Legall, J.; Moura, J. J. G.; Moura, I.; Park, J. B.; Adams, M. W. W.; Scott, R. A. (INORGANICA CHIMICA ACTA, 1998)
Fe XAS data were collected on the oxidized and reduced forms of desulforedoxin from Desulfovibrio gigas, the oxidized form of rubredoxin from Clostridium pasteurianum, and the reduced form of rubredoxin from Pyrococcus furiosus. Analysis of these data is consistent with tetrahedral FeS(4) coordination in both oxidation states, and an expansion of the Fe-S distances from 2.27 to 2.33 Angstrom upon reduction. (C) 1998 Elsevier Science S.A. All rights reserved.
33rd International Conference on Coordination Chemistry, FLORENCE, ITALY, AUG 30-SEP 04, 1998

Spectroscopic characterization of a novel tetranuclear Fe cluster in an iron-sulfur protein isolated from Desulfovibrio desulfuricans - Tavares, P; Pereira, A. S.; Krebs, C.; Ravi, N.; Moura, J. J. G.; Moura, I.; Huynh, B. H. (Biochemistry, 1998)
Mossbauer and EPR spectroscopies were used to characterize the Fe clusters in an Fe-S protein isolated from Desulfovibrio desulfuricans (ATCC 27774). This protein was previously thought to contain hexanuclear Fe clusters, but a recent X-ray crystallographic measurement on a similar protein isolated from Desulfovibrio vulgaris showed that the protein contains two tetranuclear clusters, a cubane-type [4Fe-4S] cluster and a mixed-ligand cluster of novel structure [Lindley et al. (1997) Abstract, Chemistry of Metals in Biological Systems, European Research Conference, Tomar, Portugal]. Three protein samples poised at different redox potentials (as-purified, 40 and 320 mV) were investigated. In all three samples, the [4Fe-4S] cluster was found to be present in the diamagnetic 2+ oxidation state and exhibited typical Mossbauer spectra. The novel-structure cluster was found to be redox active. In the 320-mV and as-purified samples, the cluster is at a redox equilibrium between its fully oxidized and one-electron reduced states. In the 40-mV sample, the cluster is in a two-electron reduced state. Distinct spectral components associated with the four Fe sites of cluster 2 in the three oxidation states were identified. The spectroscopic parameters obtained for the Fe sites reflect different ligand environments, making it possible to assign the spectral components to individual Fe sites. In the fully oxidized state, all four iron ions are high-spin ferric and antiferromagnetically coupled to form a diamagnetic S = 0 state. In the one-electron and two-electron reduced states, the reducing electrons were found to localize, consecutively, onto two Fe sites that are rich in oxygen/nitrogen ligands. Based on the X-ray structure and the Mossbauer parameters, attempts could be made to identify the reduced Fe sites. For the two-electron reduced cluster, EPR and Mossbauer data indicate that the cluster is paramagnetic with a nonzero interger spin. For the one-electron reduced cluster, the data suggest a half-integer spin of 9/2 Characteristic fine and hyperfine parameters for all four Fe sites were obtained. Structural implications and the nature of the spin-coupling interactions are discussed.
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Structure and function of the xanthine-oxidase family of molybdenum enzymes - Romao, M. J.; Huber, R. (Metal Sites in Proteins and Models, 1998)
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Times Cited: 32 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 32

Substrate oxidation in the active site of xanthine oxidase and related enzymes. A model density functional study - Voityuk, A. A.; Albert, K.; Romao, M. J.; Huber, R.; Rosch, N. (Inorganic Chemistry, 1998)
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Times Cited: 35 Roesch, Notker/C-1182-2010; Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 35

Thermodynamic and steady-state fluorescence emission studies on metal complexes of receptors containing benzene subunits - Bernardo, M. A.; Pina, F; Garcia-Espana, E; Latorre, J.; Luis, SV; Llinares, J. M.; Ramirez, J. A.; Soriano, C (Inorganic Chemistry, 1998)
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Times Cited: 37 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 38

Thermodynamics and kinetics of flavylium salts - Malvin revisited - Pina, F (Journal of the Chemical Society-Faraday Transactions, 1998)
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Times Cited: 36 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 37

Thermodynamics and kinetics of flavylium salts - Malvin revisited (vol 94, pg 2109, 1998) - Pina, F (Journal of the Chemical Society-Faraday Transactions, 1998)
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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

"Ventricular Late Potential Analysis with Musical and Harmonic Wavelets - Batista, A.G.; English, MJ (Medical Engineering and Physics, 1998)
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The primary structure of the split-Soret cytochrome c from Desulfovibrio desulfuricans ATCC 27774 reveals an unusual type of diheme cytochrome c - Devreese, B.; Costa, C.; Demol, H.; Papaefthymiou, V.; Moura, I.; Moura, J. J.; Van Beeumen, J. (Eur J Biochem, 1997)
The complete amino acid sequence of the unusual diheme split-Soret cytochrome c from the sulphate-reducing Desulfovibrio desulfuricans strain ATCC 27774 has been determined using classical chemical sequencing techniques and mass spectrometry. The 247-residue sequence shows almost no similarity with any other known diheme cytochrome c, but the heme-binding site of the protein is similar to that of the cytochromes c3 from the sulphate reducers. The cytochrome-c-like domain of the protein covers only the C-terminal part of the molecule, and there is evidence for at least one more domain containing four cysteine residues, which might bind another cofactor, possibly a non-heme iron-containing cluster. This domain is similar to a sequence fragment of the genome of Archaeoglobus fulgidus, which confirms the high conservation of the genes involved in sulfate reduction.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Amino Acid Sequence; Cytochrome c Group/*chemistry/classification; Desulfovibrio/*enzymology; Heme/*chemistry; Mass Spectrometry; Molecular Sequence Data; Sequence Analysis; Sequence Homology, Amino Acid; Spectroscopy, Mossbauer

Enzymatic properties and effect of ionic strength on periplasmic nitrate reductase (NAP) from Desulfovibrio desulfuricans ATCC 27774 - Bursakov, S. A.; Carneiro, C.; Almendra, M. J.; Duarte, R. O.; Caldeira, J.; Moura, I.; Moura, J. J. (Biochem Biophys Res Commun, 1997)
Some sulfate reducing bacteria can induce nitrate reductase when grown on nitrate containing media being involved in dissimilatory reduction of nitrate, an important step of the nitrogen cycle. Previously, it was reported the purification of the first soluble nitrate reductase from a sulfate-reducing bacteria Desulfovibrio desulfuricans ATCC 27774 (S.A. Bursakov, M.-Y. Liu, W.J. Payne, J. LeGall, I. Moura, and J.J.G. Moura (1995) Anaerobe 1, 55-60). The present work provides further information about this monomeric periplasmic nitrate reductase (Dd NAP). It has a molecular mass of 74 kDa, 18.6 U specific activity, KM (nitrate) = 32 microM and a pHopt in the range 8-9.5. Dd NAP has peculiar properties relatively to ionic strength and cation/anion activity responses. It is shown that monovalent cations (potassium and sodium) stimulate NAP activity and divalent (magnesium and calcium) inhibited it. Sulfate anion also acts as an activator in KPB buffer. NAP native form is protected by phosphate anion from cyanide inactivation. In the presence of phosphate, cyanide even stimulates NAP activity (up to 15 mM). This effect was used in the purification procedure to differentiate between nitrate and nitrite reductase activities, since the later is effectively blocked by cyanide. Ferricyanide has an inhibitory effect at concentrations higher than 1 mM. The N-terminal amino acid sequence has a cysteine motive C-X2-C-X3-C that is most probably involved in the coordination of the [4Fe-4S] center detected by EPR spectroscopy. The active site of the enzyme consists in a molybdopterin, which is capable for the activation of apo-nit-1 nitrate reductase of Neurospora crassa. The oxidized product of the pterin cofactor obtained by acidic hidrolysis of native NAP with sulfuric acid was identified by HPLC chromatography and characterized as a molybdopterin guanine dinucleotide (MGD).
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Alkanesulfonic Acids; Amino Acid Sequence; Buffers; Coloring Agents; Desulfovibrio/*enzymology; Drug Stability; Enzyme Activation/drug effects; Ethanolamines; Ferricyanides/pharmacology; Molecular Sequence Data; Nitrate Reductase; Nitrate Reductases/antagonists & inhibitors/chemistry/*metabolism; Nitrates/metabolism; Osmolar Concentration; Periplasm/*enzymology; Potassium Cyanide/pharmacology; Viologens/metabolism

Fe-57 Q-band pulsed ENDOR of the hetero-dinuclear site of nickel hydrogenase: Comparison of the NiA, NiB, and NiC states - Huyett, J. E.; Carepo, M.; Pamplona, A.; Franco, R.; Moura, I.; Moura, J. J. G.; Hoffman, B. M. (Journal of the American Chemical Society, 1997)
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Times Cited: 66

Nitrate and nitrite utilization in sulfate-reducing bacteria - Moura, I.; Bursakov, S.; Costa, C.; Moura, J. J. (Anaerobe, 1997)
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1075-9964 (Print)1075-9964 (Linking)Journal Article

Encapsulation of flavodoxin in reverse micelles - Andrade, S.; Kamenskaya, E. O.; Levashov, A. V.; Moura, J. J. (Biochem Biophys Res Commun, 1997)
The regulation of the properties of Desulfovibrio gigas flavodoxin in AOT/water/iso-octane micellar system was studied. UV-visible spectroscopic studies have shown that photoreduction of flavodoxin in the presence of EDTA leads to hydroquinone formation through the intermediate semiquinone. The [free FMN] - [bound to flavodoxin FMN] equilibrium (and hence, the amount of apoprotein) depends on redox state of FMN and on hydration degree which controls the micellar size. Thus, a new method of reversible cofactor removing under mild conditions (at low hydration degree of micelles) is suggested, accompained by isolation of apo-form of the protein.
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Desulfovibrio/chemistry; Flavodoxin/*chemistry; Micelles; Oxidation-Reduction; Spectrometry, Fluorescence

The chemistry and reactivity of aryl radicals - The C-C bond formation from o-bromobenzylphenylethers with tin hydride and azobisisobutyronitrile - Rosa, A. M.; A. M. Lobo; Branco, P. S.; Prabhakar, S. (TETRAHEDRON, 1997)
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New syntheses of the Amaryllidacaea alkaloids vasconine, assoanine, oxoassoanine, pratosine and ismine by radical cyclisation - Rosa, A. M.; A. M. Lobo; Branco, P. S.; Prabhakar, S.; SadaCosta, M (TETRAHEDRON, 1997)
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Synthesis of phenanthridines by radical C-aryl-C-aryl coupling - Rosa, A. M.; A. M. Lobo; Branco, P. S.; Prabhakar, S.; Pereira, AMDL (TETRAHEDRON, 1997)
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The formate dehydrogenase isolated from the aerobe Methylobacterium sp. RXM is a molybdenum-containing protein - Duarte, R. O.; Reis, A. R.; Girio, F.; Moura, I.; Moura, J. J.; Collaco, T. A. (Biochem Biophys Res Commun, 1997)
The formate dehydrogenase (FDH) isolated from cells of Methylobacterium sp. RXM grown on molybdenum-containing mineral medium using methanol as carbon source, was partially purified (at least 90% pure as revealed by SDS-PAGE). The enzyme is unstable under oxygen and all the purification steps were conducted under strict anaerobic conditions. The molecular mass is 75 kDa (gel exclusion 300 kDa). The enzyme was characterized in terms of the kinetic parameters towards different substrates and electron acceptors, pH and temperature dependence and the effect of a wide range of compounds in the enzymatic activity. The EPR spectra of the dithionite reduced sample show, at low temperature (below 20 K), two rhombic EPR signals due to two distinct [Fe-S] centres (centre I at g-values 2.023, 1.951 and 1.933, and centre II at g-values 2.054 and 1.913). At high temperature (around 100 K) another rhombic EPR signal is optimally observed at g-values 2.002, 1.987 and 1.959 and attributed to the molybdenum site. The EPR signals assigned to the iron-sulfur centres show a strong analogy with the aldehyde oxido-reductase from Desulfovibrio gigas known to contain a Mo-pterin and two [2Fe-2S] centres and whose crystallographic structure was recently resolved.
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Chromatography, Ion Exchange; Cytoplasm/enzymology; Electron Spin Resonance Spectroscopy; Formate Dehydrogenases/*chemistry/*isolation & purification/metabolism; Gram-Negative Aerobic Bacteria/*enzymology; Hydrogen-Ion Concentration; Iron-Sulfur Proteins/chemistry/isolation & purification/metabolism; Kinetics; Molecular Weight; Molybdenum/*analysis; Spectrophotometry; Thermodynamics

Conversion of desulforedoxin into a rubredoxin center - Yu, L.; Kennedy, M.; Czaja, C.; Tavares, P; Moura, J. J.; Moura, I.; Rusnak, F. (Biochem Biophys Res Commun, 1997)
Rubredoxin and desulforedoxin both contain an Fe(S-Cys)4 center. However, the spectroscopic properties of the center in desulforedoxin differ from rubredoxin. These differences arise from a distortion of the metal site hypothesized to result from adjacent cysteine residues in the primary sequence of desulforedoxin. Two desulforedoxin mutants were generated in which either a G or P-V were inserted between adjacent cysteines. Both mutants exhibited optical spectra with maxima at 278, 345, 380, 480, and 560 nm while the low temperature X-band EPR spectra indicated highspin Fe3+ ions with large rhombic distortions (E/D = 0.21-0.23). These spectroscopic properties are distinct from wild type desulforedoxin and virtually identical to rubredoxin.
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Cysteine/chemistry; Desulfovibrio/chemistry; Electron Spin Resonance Spectroscopy; Iron-Sulfur Proteins/*chemistry; Mass Spectrometry; Mutagenesis, Site-Directed; Rubredoxins/*chemistry; Spectrophotometry, Ultraviolet

1-aza-1',3'-diaza-3,3'-sigmatropic rearrangements - A convenient synthesis of benzimidazole derivatives - Carvalho, MTVL; A. M. Lobo; Branco, P. S.; Prabhakar, S. (TETRAHEDRON LETTERS, 1997)
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Formate dehydrogenase from Desulfovibrio desulfuricans ATCC 27774: Isolation and spectroscopic characterization of the active sites (heme, iron-sulfur centers and molybdenum) - Costa, C.; Teixeira, M.; Legall, J.; Moura, J. J. G.; Moura, I. (Journal of Biological Inorganic Chemistry, 1997)
An air-stable formate dehydrogenase, an enzyme that catalyzes the oxidation of formate to CO2, was purified from a sulfate-reducing organism, Desulfovibrio desulfuricans ATCC 27774. The enzyme has a molecular mass of approximately 150 kDa (three different subunits: 88, 29 and 16 kDa) and contains three types of redox-active centers: four c-type hemes, nonheme iron arranged as two [4Fe-4S](2+/1+) centers and a molybdenum-pterin site. Selenium was also chemically detected. The enzyme specific activity is 78 units per mg of protein. Mo(V) EPR signals were observed in the native, reduced and formate-reacted states. EPR signals related to the presence of multiple low-spin hemes were also observed in the oxidized state. Upon reduction, an examination of the EPR data under appropriate conditions distinguishes two types of iron-sulfur centers, an [Fe-S] center I (g(max)=2.050, g(med)=1.947, g(min)=1.896) and an [Fe-S] center II (g(max)=2.071, g(med)=1.926, g(min)=1.865). Mossbauer spectroscopy confirmed the presence of four hemes in the low-spin state. The presence of two [4Fe-4S](2+/1+) centers was confirmed, one of these displaying very small hyperfine coupling constants in the +1 oxidation state. The midpoint redox potentials of the enzyme metal centers were also estimated.
Times Cited: 30

The primary structure of the beta subunit of Desulfovibrio desulfuricans (ATCC 27774) NiFe hydrogenase - Franco, R.; Calvete, J. J.; Thole, H. H.; Raida, M.; Moura, I.; Moura, J. J. G. (Protein and Peptide Letters, 1997)
The periplasmic [NiFe] hydrogenase isolated from Desulfovibrio (D.) desulfuricans (ATCC 27774) is a heterodimer of a 28 kDa (beta) and a 60 kDa (alpha) subunit. Here we report the complete amino acid sequence of the small (beta) polypeptide chain determined by Edman degradation of proteolytic fragments. Electrospray-ionization mass spectrometry of the native protein confirmed the sequencing results. The sequence is compared with that of D. gigas [NiFe] hydrogenase whose three-dimensional structure has been recently published.
Times Cited: 1

Electron transfer between Fe(CN)(6)(3-) and iodide promoted by supercomplexation with a polyammonium macrocycle - Pina, F; A. J. Parola; SaintMaurice, A.; Manfrin, M. F.; Moggi, L.; Indelli, T.; Scandola, F. (Journal of the Chemical Society-Dalton Transactions, 1997)
Some new properties promoted by the formation of a supercomplex between iron hexacyanometallates and the polyazamacrocycle [32]aneN(8) (1,5,9,13,17,21,25,29-octaazacyclodotrane) are described. In the presence of the polyazamacrocycle, thermal and photoinduced electron transfer from iodide to Fe(CN)(6)(3-) were observed in moderately acidic media. The thermal reaction is slow (k(obs) = 8.9 x 10(-4) s(-1), at 25 degrees C) and proceeds to an equilibrium (K = 7 M-2, at 25 degrees C). The reaction is almost isoergonic, with favorable enthalpy and unfavorable entropy changes (Delta G degrees = -4.8 kJ mol(-1), Delta H degrees = -160 kJ mol(-1), Delta S degrees = -0.54 kJ mol(-1) K-1). A photoinduced electron-transfer process, leading to additional iodide oxidation, was observed upon flash irradiation of equilibrated solutions. Following the photoinduced process, the system reverts to the thermal equilibrium in the dark. The promoting role of the macrocycle is thermodynamic for the thermal process (anodic shift in the Fe-II/III potential upon supercomplex formation) and kinetic for the photoinduced process [formation of ion-paired species between hexacyanoferrate(III) and iodide upon supercomplex formation]. The thermal reaction is reversible in basic media (where the macrocycle deprotonates and supercomplex formation is prevented), providing an example of on/off switching by pH changes of an electron-transfer reaction.
ISI Document Delivery No.: XL430Times Cited: 3 Cited Reference Count: 23 Pina, F Parola, AJ SaintMaurice, A Manfrin, MF Moggi, L Indelli, T Scandola, F Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Royal soc chemistry Cambridge

Structural transformations of the synthetic salt 4',7-dihydroxyflavylium chloride in acid and basic aqueous solutions .1. Ground state - Pina, F; Benedito, L; Melo, JM; A. J. Parola; J. C. Lima; Macanita, AL (Anales De Quimica, 1997)
A complete study of the structural pH dependent transformations of the synthetic flavylium salt 4',7-dihydroxyflavylium chloride (DHF), occurring in aqueous solutions, including the basic region, is described. The kinetic study of the transformations occurring in acidic media (quinoidal base (A) reversible arrow flavylium cation (AH(+)) reversible arrow hemiacetal (B) reversible arrow cis-chalone (C-cis) reversible arrow trans-chalcone (C-trans)) allowed to conclude that the cis-trans isomerization is faster than the tautomerization and the hydration processes, which is unique in the anthocyanins family. Results obtained with the parent compound 4'7-dimethoxyglavylium chloride (DMF) with relevance to this study are also presented. In equilibrated basic solution the existence of acid-base equilibria involving the trans-Chalcone (C-trans) and its conjugated bases, (C-trans(-) and C-trans(2)), was detected. Freshly prepared solutions at pH >7 show also the presence of a transient species identified as the ionized quinoidal base (A(-)), which is almost completely converted into C-trans(2-) with a pH dependent rate constant.
ISI Document Delivery No.: XH458Times Cited: 14 Cited Reference Count: 18 Pina, F Benedito, L Melo, JM Parola, AJ Lima, JC Macanita, AL Pina, Fernando/C-8161-2011; Macanita, Antonio/H-9284-2012; Parola, A. Jorge/F-4048-2010; Lima, Joao/F-3658-2010 Macanita, Antonio/0000-0003-0976-6654; Parola, A. Jorge/0000-0002-1333-9076; Lima, Joao/0000-0003-0528-1967 Real soc espan quimica Madrid

Adaptive control of a solar energy plant: Exploiting accessible disturbances - Coito, F.; Lemos, J. M.; Silva, RN; E. Mosca (International journal of adaptive control and signal processing, 1997)
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Cascade control of a distributed collector solar field - Silva, RN; L. M. Rato; Lemos, J. M.; Coito, F. (Journal of Process Control, 1997)
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Factores de Planeamento Físico – Espacial - Amado, Miguel (1997)

Metodologia de Aproximação Sistemática, - Amado, Miguel (Faculdade de Ciências e Tecnologia, 1997)

Reevaluation of the redox and redox-Bohr cooperativity in tetrahaem Desulfovibrio vulgaris (Miyazaki F) cytochrome c3 - Salgueiro, C.A.; Turner, David L.; Legall, Jean; Xavier, António V.; Legall, J. (Journal of Biological Inorganic Chemistry, 1997)
The thermodynamic model of five interacting charge centres (four haems and an ionisable centre), which was used in the characterisation of the thermodynamic properties of Desulfovibrio vulgaris (Hildenborough) cytochrome c3 (c3DvH), is now used to reevaluate the thermodynamic properties in Desulfovibrio vulgaris (Miyazaki F) cytochrome c3 (c3DvM) on the basis of published data (Park, J.-S., Ohmura, T., Kano, K., Sagara, T., Niki, K., Kyogoku, Y. and Akutsu, H. (1996) Biochim. Biophys. Acta 1293, 45–54). Contrary to the assertion of Park et al. (1996), the pH dependence of the proton chemical shifts of haem methyls in c3DvM in several stages of oxidation is well described by the model, which involves both homotropic (e–/e–) and heterotropic (e–/H+) cooperativity. This shows that the pH dependence observed for c3DvM is not significantly more complicated than that observed for c3DvH. Since the parameters which we now obtain for c3DvM are generated with the same model as those from c3DvH, albeit using less precise data, it is possible to make a preliminary comparison of the thermodynamic properties of these two proteins and of their role in energy transduction. The extrinsic dipolar shifts generated for each methyl group by each of the four haems in c3DvM are also determined. A novel method for approximating the magnetic susceptibility tensors is used: the orientations of the principal axes of the tensors have been shown to be closely related to the geometry of the axial ligands, which is available from the X-ray structure of c3DvM, and the components of the tensors are extrapolated from EPR g values. The inclusion of the calculated haem extrinsic contributions clearly describes the pH dependence of the haem methyls in the core of the protein, close to other haems. This description is most remarkable in the case of the haem methyl 21CH3 II I, for which the "unusual pH dependence" commented on by Park et al. (1996) is easily explained using the thermodynamic parameters determined by our model together with the calculated extrinsic dipolar shifts, thus providing a test of the analysis.

Use of Paramagnetic NMR Probes for Structural Analysis in Cytochrome c3 from Desulfovibrio Vulgaris - Salgueiro, C.A.; Turner, David L.; Xavier, António V. (European Journal of Biochemistry, 1997)
The dipolar field generated by each of the four haems in the tetrahaem ferricytochrome c3 from Desulfovibrio vulgaris (Hildenborough) (c3DvH) is determined by means of a novel procedure. In this method the 13C chemical shifts of the nuclei directly bound to the haems are used to determine the in-plane orientations of the rhombic perturbation in each of the four haems with respect to a model of molecular orbitals of eg symmetry which are subject to a rhombic perturbation [Turner, D. L., Salgueiro, C. A., Schenkels, P., LeGall, J. & Xavier, A. V. (1995) Biochim. Biophys. Acta 1246, 24–28]. These orientations, together with the components of the magnetic susceptibility tensors obtained from the EPR g values and the crystal structure of c3DvH, can be used to calculate the dipolar shifts induced by each haem throughout the protein. Thus the observed 13C paramagnetic shifts of the c3DvH haem substituents were fitted considering both the pseudocontact and contact shifts of each haem simultaneously. The dipolar shifts calculated by this method were tested against the observed dipolar shifts for some amino acid residues strategically placed in the protein and also for the haem propionate groups. The effect of considering the calculated dipolar extrinsic shifts on the behaviour of the chemical shifts of the haem methyl groups in the intermediate stages of oxidation at different pH values was also analysed. The several tests applied to the calculated dipolar shifts have shown that the method is extremely useful for predicting chemical shifts as an aid to complete proton assignment, and to add further constraints in the refinement of solution structures of paramagnetic proteins and hence to probe subtle structural rearrangements around the haem pocket.

The 2.4 angstrom resolution crystal structure of boar seminal plasma PSP-I/PSP-II: a zona pellucida-binding glycoprotein heterodimer of the spermadhesin family built by a CUB domain architecture - Varela, P. F.; Romero, A.; Sanz, L.; Romao, M. J.; Topfer-Petersen, E.; Calvete, J. J. (Journal of Molecular Biology, 1997)
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Times Cited: 65 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 65

Adaptive control of a solar energy plant: Exploiting accessible disturbances - Coito, F.; Lemos, J. M.; Silva, RN; E. Mosca (International journal of adaptive control and signal processing, 1997)
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Cascade control of a distributed collector solar field - Silva, RN; L. M. Rato; Lemos, J. M.; Coito, F. (Journal of Process Control, 1997)
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Conversion of desulforedoxin into a rubredoxin center - Yu, L.; Kennedy, M.; Czaja, C.; Tavares, P; Moura, J. J. G.; Moura, I.; Rusnak, F. (Biochemical And Biophysical Research Communications, 1997)
Rubredoxin and desulforedoxin both contain an Fe(S-Cys)(4) center, However the spectroscopic properties of the center in desulforedoxin differ from rubredoxin, These differences arise from a distortion of the metal site hypothesized to result from adjacent cysteine residues in the primary sequence of desulforedoxin. Two desulforedoxin mutants were generated in which either a G or P-V were inserted between adjacent cysteines. Both mutants exhibited optical spectra with maxima at 278, 345, 380, 480, and 560 nm while the low temperature X-band EPR spectra indicated high-spin Fe3+ ions with large rhombic distortions (E/D = 0.21-0.23). These spectroscopic properties are distinct from wild type desulforedoxin and virtually identical to rubredoxin. (C) 1997 Academic Press.
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Crystal structure and mechanism of action of the xanthine oxidase-related aldehyde oxidoreductase from Desulfovibrio gigas - Romao, M. J.; Hubert, R. (Biochemical Society Transactions, 1997)
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Times Cited: 6 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; Symposium on Xanthine Oxidase - Enzymology and Pathophysiology, at the 661st Meeting of the Biochemical-Society Apr 10-11, 1997 Bath, england Biochem Soc; Soc Free Rad Res 6

Crystal structure of acidic seminal fluid protein (aSFP) at 1.9 angstrom resolution: a bovine polypeptide of the spermadhesin family - Romao, M. J.; Kolln, I.; Dias, J. M.; Carvalho, A. L.; Romero, A.; Varela, P. F.; Sanz, L.; Topfer-Petersen, E.; Calvete, J. J. (Journal of Molecular Biology, 1997)
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Times Cited: 34 Carvalho, Ana Luisa/G-5638-2011; Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Carvalho, Ana Luisa/0000-0002-3824-0240; Romao, Maria/0000-0002-3004-0543; 34

Crystal structure of cytochrome c' from Rhodocyclus gelatinosus and comparison with other cytochromes c' - Archer, M.; Banci, L.; Dikaya, E.; Romao, M. J. (Journal of Biological Inorganic Chemistry, 1997)
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Times Cited: 14 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 15

The crystal structures of two spermadhesins reveal the CUB domain fold - Romero, A.; Romao, M. J.; Varela, P. F.; Kolln, I.; Dias, J. M.; Carvalho, A. L.; Sanz, L.; TopferPetersen, E.; Calvete, J. J. (Nature Structural Biology, 1997)
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Times Cited: 110 Carvalho, Ana Luisa/G-5638-2011; Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Carvalho, Ana Luisa/0000-0002-3824-0240; Romao, Maria/0000-0002-3004-0543; 114

Crystallization and preliminary x-ray diffraction studies of aSFP, a bovine seminal plasma protein with a single CUB domain architecture - Dias, J. M.; Carvalho, A. L.; Kolln, I.; Calvete, J. J.; TopferPetersen, E.; Varela, P. F.; Romero, A.; Urbanke, C.; Romao, M. J. (Protein Science, 1997)
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Times Cited: 7 Carvalho, Ana Luisa/G-5638-2011; Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Carvalho, Ana Luisa/0000-0002-3824-0240; Romao, Maria/0000-0002-3004-0543; 7

An easy and inexpensive flash spectroscopy experiment - Maestri, M; Ballardini, R; Pina, F; Melo, MJ (Journal of Chemical Education, 1997)
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Times Cited: 25 Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; 25

Flash photolysis of 4',7-dihydroxyflavylium perchlorate - Pina, F; Melo, MJ; Ballardini, R; Flamigni, L.; Maestri, M (New Journal of Chemistry, 1997)
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Times Cited: 37 Flamigni, Lucia/B-4058-2009; Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; 37

The molybdenum site in the xanthine oxidase-related aldehyde oxidoreductase from Desulfovibrio gigas and a catalytic mechanism for this class of enzymes - Romao, M. J.; Rosch, N.; Huber, R. (Journal of Biological Inorganic Chemistry, 1997)
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Times Cited: 23 Roesch, Notker/C-1182-2010; Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 23

Mossbauer spectroscopic and kinetic characterization of ferric clusters formed in h-chain ferritin mineralization. - Tavares, P; Pereira, A. S.; Lloyd, S. G.; Danger, D; Edmondson, D. E.; Theil, EC; Huynh, B. H. (Abstracts Of Papers Of The American Chemical Society, 1997)
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Multirate MUSMAR cascade control of a distributed solar field - L. Rato; Silva, RN; Lemos, J. M.; Coito, F. (Proc. of the European Control Conference ECC97. Brussels, Belgium, 1997)
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Photochromism of 4'-methoxyflavylium perchlorate. A ''write-lock-read-unlock-erase'' molecular switching system - Pina, F; Melo, MJ; Maestri, M; Ballardini, R; Balzani, V. (Journal of the American Chemical Society, 1997)
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Times Cited: 106 Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; 106

Prediction of alternative structures of the molybdenum site in the xanthine oxidase-related aldehyde oxide reductase - Voityuk, A. A.; Albert, K.; Kostlmeier, S.; Nasluzov, V. A.; Neyman, K. M.; Hof, P.; Huber, R.; Romao, M. J.; Rosch, N. (Journal of the American Chemical Society, 1997)
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Times Cited: 33 Gemming, Sibylle/C-6898-2009; Roesch, Notker/C-1182-2010; Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013; Neyman, Konstantin/F-4055-2011 Romao, Maria/0000-0002-3004-0543; Neyman, Konstantin/0000-0002-5242-5567 33

Rapid and parallel formation of Fe3+ multimers, including a trimer, during H-type subunit ferritin mineralization - Pereira, A. S.; Tavares, P; Lloyd, S. G.; Danger, D; Edmondson, D. E.; Theil, EC; Huynh, B. H. (Biochemistry, 1997)
Conversion of Fe ions in solution to the solid phase in ferritin concentrates iron required for cell function. The rate of the Fe phase transition in ferritin is tissue specific and reflects the differential expression of two classes of ferritin subunits (H and L). Early stages of mineralization were probed by rapid freeze-quench Mossbauer, at strong fields (up to 8 T), and EPR spectroscopy in an H-type subunit, recombinant frog ferritin; small numbers of Fe (36 moles/mol of protein) were used to increase Fe3+ in mineral precursor forms, At 25 ms, four Fe3+-oxy species (three Fe dimers and one Fe trimer) were identified, These Fe3+-oxy species were found to form at similar rates and decay subsequently to a distinctive superparamagentic species designated the `'young core.'' The rate of oxidation of Fe2+ (1026 s(-1)) corresponded well to the formation constant for the Fe3+- tyrosinate complex (920 s(-1)) observed previously [Waldo, G. S., \& Theil, E. C. (1993) Biochemistry 32, 13261] and, coupled with EPR data, indicates that several or possibly all of the Fe3+-oxy species involve tyrosine. The results, combined with previous Mossbauer studies of Y30F human H-type ferritin which showed decreases in several Fe3+ intermediates and stabilization of Fe2+ [Bauminger, E. R., et al. (1993) Biochem, J. 296, 709], emphasize the involvement of tyrosyl residues in the mineralization of H-type ferritins. The subsequent decay of these multiple Fe3+-oxy species to the superparamagnetic mineral suggests that Fe3+ species in different environments may be translocated as intact units from the protein shell into the ferritin cavity where the conversion to a solid mineral occurs.
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Structure and function of molybdopterin containing enzymes - Romao, M. J.; Knablein, J.; Huber, R.; Moura, J. J. (Prog Biophys Mol Biol, 1997)
Molybdopterin containing enzymes are present in a wide range of living systems and have been known for several decades. However, only in the past two years have the first crystal structures been reported for this type of enzyme. This has represented a major breakthrough in this field. The enzymes share common structural features, but reveal different polypeptide folding topologies. In this review we give an account of the related spectroscopic information and the crystallographic results, with emphasis on structure-function studies.
0079-6107 (Print)0079-6107 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tReview
Keywords: *Iron-Sulfur Proteins; *Protein Conformation; Coenzymes/metabolism; Crystallography, X-Ray; Desulfovibrio/enzymology; Escherichia coli/enzymology; Metalloproteins/analysis/*metabolism; Models, Molecular; Molybdenum/metabolism; Oxidoreductases Acting on Sulfur Group Donors/*chemistry/metabolism; Oxidoreductases/*chemistry/metabolism; Pteridines/analysis/*metabolism; Rhodobacter sphaeroides/enzymology; Xanthine Oxidase/*chemistry/metabolism

Structure and function of molybdopterin containing enzymes - Romao, M. J.; Knablein, J.; Huber, R.; Moura, J. J. G. (Progress in Biophysics & Molecular Biology, 1997)
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Times Cited: 68 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; 68

The three-dimensional structure of mammalian spermadhesins determined by x-ray crystallography - Romero, A.; Varela, P. F.; Romao, M. J.; Sanz, L.; TopferPetersen, E.; Calvete, J. J. (European Journal of Cell Biology, 1997)
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Times Cited: 0 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 46 0

Conversion of adrenaline to indolic derivatives by the human erythrocyte plasma membrane - Marques, F.; Duarte, R. O.; Moura, J. J.; Bicho, M. P. (Biol Signals, 1996)
The conversion of adrenaline to aminochromes by the human erythrocyte plasma membranes at pH 9.5 was shown to be a complex reaction that proceeded at least by two distinct phases. The first one, corresponding to the formation of adrenochrome, is catalyzed in the presence of the membranes, suggesting the involvement of an enzyme-mediated process. Active oxygen species were identified as intermediates during this phase. Oxygen radical scavengers (catalase and superoxide dismutase) suggested H2O2 and O2- involvement. Adrenochrome formation was stimulated by NADH indicating the participation of another enzyme (NADH dehydrogenase) which is known to be present in the human erythrocyte plasma membrane. The second phase, corresponding to the disappearance of adrenochrome, is also stimulated by NADH and inhibited in the presence of the membranes. In this reaction, adrenochrome is converted to aminochromes via adrenochrome semiquinone. The formation of radical species is demonstrated by EPR spectroscopy. The results led to the proposal of a mechanism for the formation of adrenochrome and other oxidation products from adrenaline.
1016-0922 (Print)1016-0922 (Linking)Journal Article
Keywords: Benzoquinones/metabolism; Epinephrine/*metabolism; Erythrocyte Membrane/*metabolism; Humans; Indoles/*metabolism; Oxidation-Reduction; Spectrophotometry

Redox properties of cytochrome c nitrite reductase from Desulfovibrio desulfuricans ATCC 27774 - Costa, C.; Moura, J. J.; Moura, I.; Wang, Y.; Huynh, B. H. (J Biol Chem, 1996)
The dissimilatory nitrite reductase from Desulfovibrio desulfuricans ATCC 27774 catalyzes the reduction of nitrite to ammonia. Previous spectroscopic investigation revealed that it is a hexaheme cytochrome containing one high spin ferric heme and five low spin ferric hemes in the oxidized enzyme. The current study uses the high resolution of Mossbauer spectroscopy to obtain redox properties of the six heme groups. Correlating the Mossbauer findings with the EPR data reveals the pairwise spin-spin coupling among four of the heme groups. The other two hemes are found to be magnetically isolated. Reduction with dithionite and reaction with CO further indicate that only the high spin heme is capable of binding small exogenous ligands. These results confirm our previous finding that Desulfovibrio desulfuricans nitrite reductase contains six heme groups and that the high spin ferric heme is the substrate and inhibitor binding site.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: *Cytochromes a1; *Cytochromes c1; Carbon Monoxide/chemistry/metabolism; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Heme/chemistry/*metabolism; Hydrogenase/metabolism; Nitrate Reductases/chemistry/*metabolism; Oxidation-Reduction; Spectroscopy, Mossbauer; Titrimetry

Functional necessity and physicochemical characteristics of the 2Fe-2S cluster in mammalian ferrochelatase - Lloyd, S. G.; Franco, R.; Moura, J. J. G.; Moura, I.; Ferreira, G. C.; Huynh, B. H. (Journal of the American Chemical Society, 1996)
The recently discovered [2Fe-2S] cluster in mouse liver ferrochelatase has been characterized using UV-vis, EPR, and Mossbauer spectroscopic techniques. Studies are reported here for the recombinant protein purified from an overproducing transformed Escherichia coli strain. A positive correlation is observed between the presence of the [2Fe-2S] cluster and the enzymatic specific activity and demonstrates the necessity of this cofactor. Chemical analysis revealed that the preparations contained up to 1.3 Fe/molecule and indicated a 1:1 stoichiometry between Fe and acid-labile sulfide. The [2Fe-2S] cluster in the as-isolated ferrochelatase exhibits a UV-vis spectrum indicative of a [2Fe-2S](2+) cluster and is EPR-silent. The 8 T Mossbauer spectrum of the Fe-57-enriched as-isolated protein is well simulated by parameters Delta E(Q) = 0.69 +/- 0.03 mm/s and delta = 0.28 +/- 0.02 mm/s and confirms the presence of a diamagnetic ground state. Upon reduction with sodium dithionite, ferrochelatase shows a near-axial EPR spectrum with g-values of 2.00, 1.93, and 1.91, consistent with a S = 1/2 mixed valent Fe3+-Fe2+ cluster. The Orbach temperature dependence of the EPR line widths was used to provide an estimate of the exchange coupling J, which was determined to be on the order of 500-650 cm(-1) (+JS(1) . S-2 model). Redox titrations monitored by UV-vis and EPR spectroscopy revealed midpoint potentials of -390 +/- 10 and -405 +/- 10 mV, respectively. Mossbauer spectra of the sodium dithionite-reduced Fe-57-enriched ferrochelatase collected at 4.2 K in the presence of magnetic fields of 60 mT and 8 T strengths were analyzed in the mixed-valent S = 1/2 ground state. Parameters for the ferric site are Delta E(Q) = 1.2 +/- 0.2 mm/s and delta = 0.28 +/- 0.03 mm/s, with somewhat anisotropic hyperfine splittings; for the ferrous site, Delta E(Q) = 3.3 +/- 0.1 mm/s and delta = 0.67 +/- 0.04 mm/s with anisotropic hyperfine splittings characteristic of high-spin ferrous ion. The similarities and differences with other characterized [2Fe-2S](+) cluster-containing proteins are discussed.
Times Cited: 28

Structure of the Ni sites in hydrogenases by X-ray absorption spectroscopy. Species variation and the effects of redox poise - Gu, Z. J.; Dong, J.; Allan, C. B.; Choudhury, S. B.; Franco, R.; Moura, J. J. G.; Legall, J.; Przybyla, A. E.; Roseboom, W.; Albracht, S. P. J.; Axley, M. J.; Scott, R. A.; et al. (Journal of the American Chemical Society, 1996)
Structural information obtained from the analysis of nickel K-edge X-ray absorption spectroscopic data of [NiFe]hydrogenases from Desulfovibrio gigas, Thiocapsa roseopersicina, Desulfovibrio desulfuricans (ATCC 27774), Escherichia coli (hydrogenase-1), Chromatium vinosum, and Alcaligenes eutrophus H16 (NAD(+)-reducing, soluble hydrogenase), poised in different redox states, is reported. The data allow the active-site structures of enzymes from several species to be compared, and allow the effects of redox poise on the structure of the nickel sites to be examined. In addition, the structure of the nickel site obtained from recent crystallographic studies of the D. gigas enzyme (Volbeda, A.; Charon, M.-H.; Piras, C.; Hatchikian, E. C.; Frey, M.; Fontecilla-Camps, J. C. Nature 1995, 373, 580-587) is compared with the structural features obtained from the analysis of XAS data from the same enzyme. The nickel sites of all but the oxidized (as isolated) sample of A. eutrophus hydrogenase are quite similar. The nickel K-edge energies shift 0.9-1.5 eV to lower energy upon reduction from oxidized (forms A and B) to fully reduced forms. This value is comparable with no more than a one-electron metal-centered oxidation state change. With the exception of T. roseopersicina hydrogenase, most of the edge energy shift (-0.8 eV) occurs upon reduction of the oxidized enzymes to the EPR-silent intermediate redox level (SI). Analysis of the XANES features assigned to 1s-->3d electronic transitions indicates that the shift in energy that occurs for reduction of the enzymes to the SI level may be attributed at least in part to an increase in the coordination number from five to six. The smallest edge energy shift is observed for the T. roseopersicina enzyme, where the XANES data indicate that the nickel center is always six-coordinate. With the exception of the oxidized sample of A. eutrophus hydrogenase, the EXAFS data are dominated by scattering from S-donor ligands at similar to 2.2 Angstrom. The enzyme obtained from T. roseopersicina also shows evidence for the presence of O,N-donor ligands. The data from A. eutrophus hydrogenase are unique in that they indicate that a significant structural change occurs upon reduction of the enzyme. EXAFS data obtained from the oxidized (as isolated) A. eutrophus enzyme indicate that the EXAFS is dominated by scattering from 3-4 N,O-donor atoms at 2.06(2) Angstrom, with contributions from 2-3 S-donor ligands at 2.35(2) Angstrom. This changes upon reduction to a more typical nickel site composed of similar to 4 S-donor ligands at a Ni-S distance of 2.19(2) Angstrom. Evidence for the presence of atoms in the 2.4-2.9 Angstrom distance range is found in most samples, particularly the reduced enzymes (SI, form C, and R). The analysis of these data is complicated by the fact that it is difficult to distinguish between S and Fe scattering atoms at this distance, and by the potential presence of both S and another metal atom at similar distances. The results of EXAFS analysis are shown to be in general agreement with the published crystal structure of the D. gigas enzyme.
Times Cited: 86

Preliminary crystallographic analysis and further characterization of a dodecaheme cytochrome c from Desulfovibrio desulfuricans ATCC 27774 - Coelho, A. V.; Matias, P. M.; Sieker, L. C.; Morais, J.; Carrondo, M. A.; Lampreia, J.; Costa, C.; Moura, J. J.; Moura, I.; Legall, J. (Acta Crystallogr D Biol Crystallogr, 1996)
Dodecaheme cytochrome c has been purified from Desulfovibrio (D.) desulfuricans ATCC 27774 cells grown under both nitrate and sulfate-respiring conditions. Therefore, it is likely to play a role in the electron-transfer system of both respiratory chains. Its molecular mass (37768 kDa) was determined by electrospray mass spectrometry. Its first 39 amino acids were sequenced and a motif was found between amino acids 32 and 37 that seems to exist in all the cytochromes of the c(3) type from sulfate-reducing bacteria sequenced at present. The midpoint redox potentials of this cytochrome were estimated to be -68, -120, -248 and -310 mV. Electron paramagnetic resonance spectroscopy of the oxidized cytochrome shows several low-spin components with a g(max) spreading from 3.254 to 2.983. Two crystalline forms were obtained by vapour diffusion from a solution containing 2% PEG 6000 and 0.25-0.75 M acetate buffer pH = 5.5. Both crystals belong to monoclinic space groups: one is P2(1), with a = 61.00, b = 106.19, c = 82.05 A, beta = 103.61 degrees, and the other is C2 with a = 152.17, b = 98.45, c = 89.24 A, beta = 119.18 degrees. Density measurements of the P2(1) crystals suggest that there are two independent molecules in the asymmetric unit. Self-rotation function calculations indicate, in both crystal forms, the presence of a non-crystallographic axis perpendicular to the crystallographic twofold axis. This result and the calculated values for the volume per unit molecular weight of the C2 crystals suggest the presence of two or four molecules in the asymmetric unit.
0907-4449 (Print)0907-4449 (Linking)Journal Article

Primary structure of desulfoferrodoxin from Desulfovibrio desulfuricans ATCC 27774, a new class of non-heme iron proteins - Devreese, B.; Tavares, P; Lampreia, J.; Van Damme, N.; Legall, J.; Moura, J. J.; Van Beeumen, J.; Moura, I. (FEBS Lett, 1996)
The primary structure of desulfoferrodoxin from Desulfovibrio desulfuricans ATCC 27774, a redox protein with two mononuclear iron sites, was determined by automatic Edman degradation and mass spectrometry of the composing peptides. It contains 125 amino acid residues of which five are cysteines. The first four, Cys-9, Cys-12, Cys-28 and Cys-29, are responsible for the binding of Center I which has a distorted tetrahedral sulfur coordination similar to that found in desulforedoxin from D. gigas. The remaining Cys-115 is proposed to be involved in the coordination of Center II, which is probably octahedrally coordinated with predominantly nitrogen/oxygen containing ligands as previously suggested by Mossbauer and Raman spectroscopy.
0014-5793 (Print)0014-5793 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Amino Acid Sequence; Binding Sites; Conserved Sequence; Desulfovibrio/*chemistry; Evolution, Molecular; Ferredoxins/*chemistry; Molecular Sequence Data; Peptides/chemistry; Sequence Alignment; Sequence Analysis; Serine Endopeptidases/metabolism; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

A single histidine is required for activity of cytochrome c peroxidase from Paracoccus denitrificans - McGinnity, D. F.; Devreese, B.; Prazeres, S.; Van Beeumen, J.; Moura, I.; Moura, J. J.; Pettigrew, G. W. (J Biol Chem, 1996)
The diheme cytochrome c peroxidase from Paracoccus denitrificans was modified with the histidine-specific reagent diethyl pyrocarbonate. At low excess of reagent, 1 mol of histidine was modified in the oxidized enzyme, and modification was associated with loss of the ability to form the active state. With time, the modification reversed, and the ability to form the active state was recovered. The agreement between the spectrophotometric measurement of histidine modification and radioactive incorporation using a radiolabeled reagent indicated little modification of other amino acids. However, the reversal of histidine modification observed spectrophotometrically was not matched by loss of radioactivity, and we propose a slow transfer of the ethoxyformyl group to an unidentified amino acid. The presence of CN- bound to the active peroxidatic site of the enzyme led to complete protection of the essential histidine from modification. Limited subtilisin treatment of the native enzyme followed by tryptic digest of the C-terminal fragment (residues 251-338) showed that radioactivity was located in a peptide containing a single histidine at position 275. We propose that this conserved residue, in a highly conserved region, is central to the function of the active mixed-valence state.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: *Histidine; *Protein Structure, Secondary; Amino Acid Sequence; Binding Sites; Carbon Radioisotopes; Chromatography, Gel; Conserved Sequence; Crystallography, X-Ray; Cyanides; Cytochrome-c Peroxidase/chemistry/isolation & purification/*metabolism; Diethyl Pyrocarbonate/metabolism/*pharmacology; Electron Spin Resonance Spectroscopy; Kinetics; Mass Spectrometry; Oxidation-Reduction; Paracoccus denitrificans/*enzymology; Peptide Fragments/chemistry/isolation & purification; Spectrophotometry, Ultraviolet; Subtilisins; Trypsin

Study of Instruments and Tools to Anticipate the Effects of Industrial Change - Portuguese report - António Moniz; Dinis, Marco (University Library of Munich, Germany, 1996)
This study was produced for the “Study of Instruments and Tools to anticipate the effects of industrial change on employment, trades and vocational qualifications” and for DG V (Employment) of the European Commission in the late 1994. It started when the previous Portuguese government was still ruling, the main policies were defined, and the available instruments were not used in a minimum extend. The new Government, issued from the 1995 elections, proposed “employment” as a major objective with horizontal responsibility. That’s also why there is now a Ministry for Qualifications and Employment, and another one for Solidarity and Social Affairs, not one for Employment and Social Affairs as the previous Government had. But more than that, this objective is considered to need a coordinated and consistent action that involves external affairs, industrial and regional policies, and the policies on education, training and employment, among others. The promotion of the “quality of employment” is being recently done at the working conditions, remuneration, social protection, occupational promotion levels, and the equality of opportunities towards employment and vocational training levels, and finally, the levels of qualification of human resources for a better labour market, education policy and training policy developments. In Portugal, the influence of the industrial change is produced in a top-down way; with (in some cases) an ex post analysis process to formulated training needs. This means that the industrial change impact is produced (normally, unexpectedly), and afterwards the responsible at the company level tries to know which training needs should be formulated in order those effects could be the smoother possible. The training needs at the company level is not based on anticipatory studies, neither is done any long term forecast on qualification, or even employment level.
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Keywords: employment; foresight; human resources; labour market; Portugal; qualifications; working conditions

{Study of Instruments and Tools to Anticipate the Effects of Industrial Change - Portuguese report} - António Moniz; Dinis, Marco (University Library of Munich, Germany, 1996)
This study was produced for the “Study of Instruments and Tools to anticipate the effects of industrial change on employment, trades and vocational qualifications” and for DG V (Employment) of the European Commission in the late 1994. It started when the previous Portuguese government was still ruling, the main policies were defined, and the available instruments were not used in a minimum extend. The new Government, issued from the 1995 elections, proposed “employment” as a major objective with horizontal responsibility. That’s also why there is now a Ministry for Qualifications and Employment, and another one for Solidarity and Social Affairs, not one for Employment and Social Affairs as the previous Government had. But more than that, this objective is considered to need a coordinated and consistent action that involves external affairs, industrial and regional policies, and the policies on education, training and employment, among others. The promotion of the “quality of employment” is being recently done at the working conditions, remuneration, social protection, occupational promotion levels, and the equality of opportunities towards employment and vocational training levels, and finally, the levels of qualification of human resources for a better labour market, education policy and training policy developments. In Portugal, the influence of the industrial change is produced in a top-down way; with (in some cases) an ex post analysis process to formulated training needs. This means that the industrial change impact is produced (normally, unexpectedly), and afterwards the responsible at the company level tries to know which training needs should be formulated in order those effects could be the smoother possible. The training needs at the company level is not based on anticipatory studies, neither is done any long term forecast on qualification, or even employment level.
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Keywords: employment; foresight; human resources; labour market; Portugal; qualifications; working conditions

Novos modelos de produção na indústria automóvel? Análise de uma fábrica de motores em Portugal [New production models in the automotive industry? Analysis of an engine factory in Portugal] - António Moniz (University Library of Munich, Germany, 1996)
This paper is based in a report for the international project “GERPISA-Labour Relations” on the concept of leader-factory, and in other papers written after that using the case study of the Renault factory in the Aveiro region. This case study is articulated with other studies on engine factories of the same company in Spain, France and Mexico. That study has been co-ordinated by Prof. Juan José Castillo (Univ. Complutense Madrid, Spain). Here we present the results of this empirical research from where were developed the first indicators of a discussion on the concept of new production models and leader-factory that have been studied by the GERPISA international network.
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Keywords: automobile; automotive industry; leader-factory; production models

Preliminary crystallographic analysis of the oxidized form of a two mono-nuclear iron centres protein from Desulfovibrio desulfuricans ATCC 27774 - Coelho, A. V.; Matias, P. M.; Carrondo, M. A.; Tavares, P; Moura, J. J.; Moura, I.; Fulop, V.; Hajdu, J.; Legall, J. (Protein Sci, 1996)
Crystals of the fully oxidized form of desulfoferrodoxin were obtained by vapor diffusion from a solution containing 20% PEG 4000, 0.1 M HEPES buffer, pH 7.5, and 0.2 M CaCl2. Trigonal and/or rectangular prisms could be obtained, depending on the temperature used for the crystal growth. Trigonal prisms belong to the rhombohedral space group R32, with a = 112.5 A and c = 63.2 A; rectangular prisms belong to the monoclinic space group C2, with a = 77.7 A, b = 80.9 A, c = 53.9 A, and beta = 98.1 degrees. The crystallographic asymmetric unit of the rhombohedral crystal form contains one molecule. There are two molecules in the asymmetric unit of the monoclinic form, in agreement with the self-rotation function.
0961-8368 (Print)0961-8368 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Crystallization; Crystallography, X-Ray; Desulfovibrio/chemistry/metabolism; Ferredoxins/*chemistry; Oxidation-Reduction

{Novos modelos de produção na indústria automóvel? Análise de uma fábrica de motores em Portugal [New production models in the automotive industry? Analysis of an engine factory in Portugal]} - António Moniz (University Library of Munich, Germany, 1996)
This paper is based in a report for the international project “GERPISA-Labour Relations” on the concept of leader-factory, and in other papers written after that using the case study of the Renault factory in the Aveiro region. This case study is articulated with other studies on engine factories of the same company in Spain, France and Mexico. That study has been co-ordinated by Prof. Juan José Castillo (Univ. Complutense Madrid, Spain). Here we present the results of this empirical research from where were developed the first indicators of a discussion on the concept of new production models and leader-factory that have been studied by the GERPISA international network.
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Keywords: automobile; automotive industry; leader-factory; production models

Crystal structure of flavodoxin from Desulfovibrio desulfuricans ATCC 27774 in two oxidation states - Romero, A.; Caldeira, J.; Legall, J.; Moura, I.; Moura, J. J.; Romao, M. J. (Eur J Biochem, 1996)
The crystal structures of the flavodoxin from Desulfovibrio desulfuricans ATCC 27774 have been determined and refined for both oxidized and semi-reduced forms to final crystallographic R-factors of 17.9% (0.8-0.205-nm resolution) and 19.4% (0.8-0.215-nm resolution) respectively. Native flavodoxin crystals were grown from ammonium sulfate with cell constants a = b = 9.59 nm, c=3.37nm (oxidized crystals) and they belong to space group P3(2)21. Semireduced crystals showed some changes in cell dimensions: a = b = 9.51 nm, c=3.35 nm. The three-dimensional structures are similar to other known flavodoxins and deviations are found essentially in the isoalloxazine ring environment. Conformational changes are observed between both redox states and a flip of the Gly61-Met62 peptide bond occurs upon one-electron reduction of the FMN group. These changes influence the redox potential of the oxidized/semiquinone couple. Modulation of the redox potentials is known to be related to the association constant of the FMN group to the protein. The flavodoxin from D. desulfuricans now studied has a large span between E2 (oxidized --> semiquinone) and E1 (semiquinone --> hydroquinone) redox potentials, both these values being substantially more positive within known flavodoxins. A comparison of their FMN environment was made in both oxidation states in order to correlate functional and structural differences.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Amino Acid Sequence; Crystallography, X-Ray; Desulfovibrio/*chemistry; Flavin Mononucleotide/metabolism; Flavodoxin/*chemistry/metabolism; Models, Molecular; Molecular Sequence Data; Oxidation-Reduction; Protein Binding; Protein Conformation; Sequence Homology, Amino Acid

Preliminary crystallographic analysis of the oxidized form of a two mono-nuclear iron centres protein from Desulfovibrio desulfuricans ATCC 27774 - Coelho, A. V.; Matias, P. M.; Carrondo, M. A.; Tavares, P; Moura, J. J. G.; Moura, I.; Fulop, V.; Hajdu, J.; Legall, J. (PROTEIN SCIENCE, 1996)
Crystals of the fully oxidized form of desulfoferrodoxin were obtained by vapor diffusion from a solution containing 20% PEG 4000, 0.1 M HEPES buffer, pH 7.5, and 0.2 M CaCl2. Trigonal and/or rectangular prisms could be obtained, depending on the temperature used for the crystal growth. Trigonal prisms belong to the rhombohedral space group R32, with a = 112.5 Angstrom and c = 63.2 Angstrom; rectangular prisms belong to the monoclinic space group C2, with a = 77.7 Angstrom, b = 80.9 Angstrom, c = 53.9 Angstrom, and beta = 98.1 degrees. The crystallographic asymmetric unit of the rhombohedral crystal form contains one molecule. There are two molecules in the asymmetric unit of the monoclinic form, in agreement with the self-rotation function.
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Hibridação de um sistema flex{\'ıvel de produção: possibilidades de aplicação do conceito de antropocentrismo [Hybridation of a flexible production system: possibilities for an application of t - António Moniz; Oliveira, Paula; Bento, Sofia (University Library of Munich, Germany, 1996)
Today one can understand the wider use of the anthropocentrism concept applied to the production architectures, emerging a new value of the intuitive capacities and human knowledge in the optimization and flexibilization of the manufacturing processes. Having a flexible production and assembly system architecture that exists at UNINOVA-CRI, we will try to develop some exploratory hypothesis on the applicability of the hybridizing concept and its repercussions in the definition of working places, in their organization and formation of working teams. We will underline some aspects that should be taken into consideration when are design such systems, including some ergonomical aspects.
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Keywords: anthropocentrism; flexibi; human-oriented systems; manufacturing processes; production architectures

{Hibridação de um sistema flexível de produção: possibilidades de aplicação do conceito de antropocentrismo [Hybridation of a flexible production system: possibilities for an application of the anth} - António Moniz; Oliveira, Paula; Bento, Sofia (University Library of Munich, Germany, 1996)
Today one can understand the wider use of the anthropocentrism concept applied to the production architectures, emerging a new value of the intuitive capacities and human knowledge in the optimization and flexibilization of the manufacturing processes. Having a flexible production and assembly system architecture that exists at UNINOVA-CRI, we will try to develop some exploratory hypothesis on the applicability of the hybridizing concept and its repercussions in the definition of working places, in their organization and formation of working teams. We will underline some aspects that should be taken into consideration when are design such systems, including some ergonomical aspects.
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Keywords: anthropocentrism; flexibi; human-oriented systems; manufacturing processes; production architectures

Characterization of a 7Fe ferredoxin isolated from the marine denitrifier Pseudomonas nautica strain 617: spectroscopic and electrochemical studies - Macedo, A. L.; Besson, S.; Moreno, C.; Fauque, G.; Moura, J. J.; Moura, I. (Biochem Biophys Res Commun, 1996)
A 7Fe ferredoxin, isolated from the marine denitrifier Pseudomonas nautica strain 617, was characterized. The NH2-terminal sequence analysis, performed until residue number 56, shows a high similarity with the 7Fe ferredoxins isolated from Azotobacter vinelandii, Pseudomonas putida, and Pseudomonas stutzeri. EPR and NMR spectroscopies identify the presence of both [3Fe-4S] and [4Fe-4S] clusters, with cysteinyl coordination. The electrochemical studies on [Fe-S] clusters show that a fast diffusion-dominated electron transfer, promoted by Mg(II), takes place between the ferredoxin and the glassy carbon electrode. Square wave voltammetry studies gave access to the electrosynthesis of a 4Fe center formed within the [3Fe-4S] core. The [3Fe-4S] cluster exhibited two reduction potentials at -175 and -680 +/- 10 mV and the [4Fe-4S] cluster was characterized by an unusually low reduction potential of -715 +/- 10 mV, at pH 7.6
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Amino Acid Sequence; Electrochemistry; Electron Spin Resonance Spectroscopy; Ferredoxins/*chemistry/isolation & purification; Magnetic Resonance Spectroscopy; Molecular Sequence Data; Pseudomonas/*chemistry; Sequence Homology, Amino Acid

A structure-based catalytic mechanism for the xanthine oxidase family of molybdenum enzymes - Huber, R.; Hof, P.; Duarte, R. O.; Moura, J. J.; Moura, I.; Liu, M. Y.; Legall, J.; Hille, R.; Archer, M.; Romao, M. J. (Proc Natl Acad Sci U S A, 1996)
The crystal structure of the xanthine oxidase-related molybdenum-iron protein aldehyde oxido-reductase from the sulfate reducing anaerobic Gram-negative bacterium Desulfovibrio gigas (Mop) was analyzed in its desulfo-, sulfo-, oxidized, reduced, and alcohol-bound forms at 1.8-A resolution. In the sulfo-form the molybdenum molybdopterin cytosine dinucleotide cofactor has a dithiolene-bound fac-[Mo, = O, = S, ---(OH2)] substructure. Bound inhibitory isopropanol in the inner compartment of the substrate binding tunnel is a model for the Michaelis complex of the reaction with aldehydes (H-C = O,-R). The reaction is proposed to proceed by transfer of the molybdenum-bound water molecule as OH- after proton transfer to Glu-869 to the carbonyl carbon of the substrate in concert with hydride transfer to the sulfido group to generate [MoIV, = O, -SH, ---(O-C = O, -R)). Dissociation of the carboxylic acid product may be facilitated by transient binding of Glu-869 to the molybdenum. The metal-bound water is replenished from a chain of internal water molecules. A second alcohol binding site in the spacious outer compartment may cause the strong substrate inhibition observed. This compartment is the putative binding site of large inhibitors of xanthine oxidase.
0027-8424 (Print)0027-8424 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov't
Keywords: Aldehyde Oxidoreductases/chemistry/classification/*metabolism; Bacterial Proteins/*chemistry/metabolism; Crystallography, X-Ray; Cytosine Nucleotides/chemistry; Desulfovibrio/*enzymology; Models, Molecular; Molybdenum/*chemistry/metabolism; Oxidation-Reduction; Pterins/chemistry; Xanthine Oxidase/*chemistry/classification/metabolism

EPR and Mossbauer spectroscopic studies on enoate reductase - Caldeira, J.; Feicht, R.; White, H.; Teixeira, M.; Moura, J. J.; Simon, H.; Moura, I. (J Biol Chem, 1996)
Enoate reductase (EC 1.3.1.31) is a protein isolated from Clostridium tyrobutyricum that contains iron, labile sulfide, FAD, and FMN. The enzyme reduces the alpha,beta carbon-carbon double bond of nonactivated 2-enoates and in a reversible way that of 2-enals at the expense of NADH or reduced methyl viologen. UV-visible and EPR potentiometric titrations detect a semiquinone species in redox intermediate states characterized by an isotropic EPR signal at g = 2.0 without contribution at 580 nm. EPR redox titration shows two widely spread mid-point redox potentials (-190 and -350 mV at pH 7. 0), and a nearly stoichiometric amount of this species is detected. The data suggest the semiquinone radical has an anionic nature. In the reduced form, the [Fe-S] moiety is characterized by a single rhombic EPR spectrum, observed in a wide range of temperatures (4. 2-60 K) with g values at 2.013, 1.943, and 1.860 (-180 mV at pH 7.0). The gmax value is low when compared with what has been reported for other iron-sulfur clusters. Mossbauer studies reveal the presence of a [4Fe-4S]+2/+1 center. One of the subcomponents of the spectrum shows an unusually large value of quadrupole splitting (ferrous character) in both the oxidized and reduced states. Substrate binding to the reduced enzyme induces subtle changes in the spectroscopic Mossbauer parameters. The Mossbauer data together with known kinetic information suggest the involvement of this iron-sulfur center in the enzyme mechanism.
0021-9258 (Print)0021-9258 (Linking)Journal Article
Keywords: *Oxidoreductases Acting on CH-CH Group Donors; Binding Sites; Catalysis; Clostridium/enzymology; Electron Spin Resonance Spectroscopy; Iron-Sulfur Proteins/chemistry/metabolism; Iron/chemistry; Kinetics; Molecular Structure; Oxidation-Reduction; Oxidoreductases/*chemistry/metabolism; Spectrophotometry; Spectroscopy, Mossbauer; Substrate Specificity; Sulfur/chemistry; Temperature

The solution structure of desulforedoxin, a simple iron-sulfur protein - An NMR study of the zinc derivative - Goodfellow, B. J.; Tavares, P; Romao, M. J.; Czaja, C.; Rusnak, F.; Legall, J.; Moura, I.; Moura, J. J. G. (Journal of Biological Inorganic Chemistry, 1996)
Desulforedoxin is a simple dimeric protein isolated from Desulfovibrio gigas containing a distorted rubredoxin-like center with one iron coordinated by four cysteinyl residues (7.9 kDa with a 36-amino-acid monomer). H-1 NMR spectra of the oxidized Dx(Fe3+) and reduced Dx(Fe2+) forms were analyzed. The spectra show substantial line broadening due to the paramagnetism of iron. However, very low-field-shifted resonances, assigned to H beta protons, were observed in the reduced state and their temperature dependence analyzed. The active site of Dx was reconstituted with zinc, and its solution structure was determined using 2D NMR methods. This diamagnetic form gave high-resolution NMR data enabling the identification of all the amino acid spin systems. Sequential assignment and the determination of secondary structural elements was attempted using 2D NOESY experiments. However, because of the symmetrical dimer nature of the protein standard, NMR sequential assignment methods could not resolve all cross peaks due to inter- and intra-chain effects. The X-ray structure enabled the spatial relationship between the monomers to be obtained, and resolved the assignment problems. Secondary structural features could be identified from the NMR data; an antiparallel beta-sheet running from D5 to V18 with a well-defined beta-turn around cysteines C9 and C12. The section G22 to T25 is poorly defined by the NMR data and is followed by a turn around V27-C29. The C-terminus ends up near residues V6 and Y7. Distance geometry (DG) calculations allowed families of structures to be generated from the NMR data. A family of structures with a low target function violation for the Dr monomer and dimer were found to have secondary structural elements identical to those seen in the X-ray structure. The amide protons for G4, D5, G13, L11 NH and Q14 NH epsilon amide protons, H-bonded in the X-ray structure, were not seen by NMR as slowly exchanging, while structural disorder at the N-terminus, for the backbone at E10 and for the section G22-T25, was observed. Comparison between the Fe and Zn forms of Dr suggests that metal substitution does not have an effect on the structure of the protein.
Times Cited: 12

The solution structure of desulforedoxin, a simple iron-sulfur protein - An NMR study of the zinc derivative - Goodfellow, B. J.; Tavares, P; Romão, M.J.; Czaja, C.; Rusnak, F.; Legall, J.; Moura, I.; Moura, J. J. G. (JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY, 1996)
Desulforedoxin is a simple dimeric protein isolated from Desulfovibrio gigas containing a distorted rubredoxin-like center with one iron coordinated by four cysteinyl residues (7.9 kDa with a 36-amino-acid monomer). H-1 NMR spectra of the oxidized Dx(Fe3+) and reduced Dx(Fe2+) forms were analyzed. The spectra show substantial line broadening due to the paramagnetism of iron. However, very low-field-shifted resonances, assigned to H beta protons, were observed in the reduced state and their temperature dependence analyzed. The active site of Dx was reconstituted with zinc, and its solution structure was determined using 2D NMR methods. This diamagnetic form gave high-resolution NMR data enabling the identification of all the amino acid spin systems. Sequential assignment and the determination of secondary structural elements was attempted using 2D NOESY experiments. However, because of the symmetrical dimer nature of the protein standard, NMR sequential assignment methods could not resolve all cross peaks due to inter- and intra-chain effects. The X-ray structure enabled the spatial relationship between the monomers to be obtained, and resolved the assignment problems. Secondary structural features could be identified from the NMR data; an antiparallel beta-sheet running from D5 to V18 with a well-defined beta-turn around cysteines C9 and C12. The section G22 to T25 is poorly defined by the NMR data and is followed by a turn around V27-C29. The C-terminus ends up near residues V6 and Y7. Distance geometry (DG) calculations allowed families of structures to be generated from the NMR data. A family of structures with a low target function violation for the Dr monomer and dimer were found to have secondary structural elements identical to those seen in the X-ray structure. The amide protons for G4, D5, G13, L11 NH and Q14 NH epsilon amide protons, H-bonded in the X-ray structure, were not seen by NMR as slowly exchanging, while structural disorder at the N-terminus, for the backbone at E10 and for the section G22-T25, was observed. Comparison between the Fe and Zn forms of Dr suggests that metal substitution does not have an effect on the structure of the protein.
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A synthesis of the Amaryllidaceae alkaloid pratosine - Pereira, M. M. A.; Prabhakar, S.; A. M. Lobo (JOURNAL OF NATURAL PRODUCTS, 1996)
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Characterization of representative enzymes from a sulfate reducing bacterium implicated in the corrosion of steel - Pereira, A. S.; Franco, R.; Feio, M. J.; Pinto, C.; Lampreia, J.; Reis, M. A.; Calvete, J.; Moura, I.; Beech, I.; Lino, A. R.; Moura, J. J. (Biochem Biophys Res Commun, 1996)
This communication reports the isolation, purification and characterization of key enzymes involved in dissimilatory sulfate reduction of a sulfate reducing bacterium classified as Desulfovibrio desulfuricans subspecies desulfuricans New Jersey (NCIMB 8313) (Ddd NJ). The chosen strain, originally recovered from a corroding cast iron heat exchanger, was grown in large scale batch cultures. Physico-chemical and spectroscopic studies of the purified enzymes were carried out. These analyses revealed a high degree of similarity between proteins isolated from the DddNJ strain and the homologous proteins obtained from Desulfomicrobium baculatus Norway 4. In view of the results obtained, taxonomic reclassification of Desulfovibrio desulfuricans subspecies desulfuricans New Jersey (NCIMB 8313) into Desulfomicrobium baculatus (New Jersey) is proposed.
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Corrosion; Cytochrome c Group/*metabolism; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Oxidation-Reduction; Oxidoreductases Acting on Sulfur Group Donors/*metabolism; Oxidoreductases/*metabolism; Steel/*chemistry

Analysis, design and engineering of simple iron-sulfur proteins: Tales from rubredoxin and desulforedoxin - Moura, J. J. G.; Goodfellow, B. J.; Romao, M. J.; Rusnak, F.; Moura, I. (Comments on Inorganic Chemistry, 1996)
The most thoroughly characterized non-heme iron center in biology is Rubredoxin, the simplest member of the iron-sulfur: class of metalloproteins. Rubredoxin contains a high-spin iron atom with tetrahedral coordination by four cysteinyl sulfur atoms. A structural variant of this center is found in Desulforedoxin, the smallest known Rubredoxin type protein. The 3D structure of both Rd and Dr has been determined at high resolution. These two proteins can therefore be used as case studies in which structural control by the polypeptide chain over the metal site can be discussed in detail.
Times Cited: 10Part a

Photochemistry of 3,4'-dimethoxy-7-hydroxyflavylium chloride - Photochromism and excited-state proton transfer - Pina, F; Benedito, L; Melo, MJ; A. J. Parola; Bernardo, A. (Journal of the Chemical Society-Faraday Transactions, 1996)
The synthetic compound 3,4'-dimethoxy-7-hydroxyflavylium chloride gives rise, in aqueous solution at moderately acidic pH, to a pH-dependent equilibrium between the flavylium cation, hemiacetal, (Z)-chalcone and a small amount of quinonoidal base. The distribution, as a function of pH, of the molar fractions of the several species present in solution have been calculated on the basis of H-1 NMR and pH jump experiments monitored by stopped-flow and conventional UV-VIS spectrophotometry, and highperformance liquid chromatography (HPLC). The compound shows interesting photochemical properties: (i) at pH 4.0 it presents a photochromic effect that converts (Z)-chalcone into hemiacetal, the reaction being reversible in the dark and (ii) excited-state proton transfer is observed between the flavylium cation and quinonoidal base. An appropriate formalism to quantify the experimental results has been developed. The formalism allows determination of the pH-dependent molar fraction distribution of the several anthocyanin forms present at equilibrium, as well as predicting the distribution of the molar fractions prior to equilibrium.
ISI Document Delivery No.: UN958Times Cited: 31 Cited Reference Count: 17 Pina, F Benedito, L Melo, MJ Parola, AJ Bernardo, A Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Royal soc chemistry Cambridge

Photoinduced electron- and energy-transfer processes of biacetyl imprisoned in a hemicarcerand - A. J. Parola; Pina, F; Ferreira, E.; Maestri, M; Balzani, V. (Journal of the American Chemical Society, 1996)
The energy- and electron-transfer quenching processes of the lowest triplet excited state of biacetyl (2,3-butanedione) imprisoned in a hemicarcerand have been systematically investigated in CH2Cl2 solution at room temperature. Twenty potential quenchers have been used, including ten triplet energy accepters (mostly, aromatic hydrocarbons) and nine electron donors (mostly, aromatic amines). Bimolecular rate constants for the quenching processes were obtained by Stern-Volmer analysis and compared with those found for the quenching of free biacetyl. In the electron-transfer processes, aromatic amines with oxidation potential from +0.015 V (N,N,N',N'-tetramethyl-p-phenylenediamine) to +0.83 V (diphenylamine) quench free biacetyl at the diffusion-controlled limit, whereas for imprisoned biacetyl the rate constant decreases (roughly in a linear manner) from 4.0 x 10(8) to 1.2 x 10(5) M(-1) s(-1) As far as energy-transfer is concerned, the rate constant for the quenching of free biacetyl increases with decreasing Delta G degrees and reaches the diffusion-controlled plateau value (k(q) similar to 10(10) M(-1) s(-1)) for Delta G degrees similar to 0.1 eV, whereas for imprisoned biacetyl a scattered, bell-shaped log k(q) vs Delta G degrees plot is obtained, with a maximum value (similar to 10(6) M(-1) s(-1)) much below the diffusion-controlled limit. The results obtained show that the walls of the hemicarcerand allow only very weak electronic interaction between incarcerated triplet biacetyl and external quenchers. A brief discussion of the results obtained in the light of current energy- and electron-transfer theories is presented.
ISI Document Delivery No.: VU995Times Cited: 41 Cited Reference Count: 61 Parola, AJ Pina, F Ferreira, E Maestri, M Balzani, V Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Amer chemical soc Washington

Photophysics of supercomplexes. Adduct between Ru(bpy)(CN)(4)(2-) and the 32 ane-N8H88+ polyaza macrocycle - Rampi, M. A.; Indelli, M. T.; Scandola, F.; Pina, F; A. J. Parola (Inorganic Chemistry, 1996)
The formation of a supercomplex between the Ru(bpy)(CN)(4)(2-) (bpy = 2,2'-bipyridine) complex and the [32]-ane-N8H88+ macrocycle (1) has been studied in water and in acetonitrile. In acetonitrile, supercomplex formation is accompanied by (i) large hypsochromic shifts in the absorption spectrum (color changes from deep violet to yellow) and in the emission spectrum, (ii) large anodic shifts in standard oxidation (0.73 V) and reduction (0.37 V) potentials, (iii) typical shifts of H-1-NMR signals for the macrocycle N-bound protons and the complex bipyridine protons, and (iv) a large increase in the MLCT excited-state lifetime of the complex. In water, the spectral shifts and the changes in standard potential are much less pronounced, but supercomplex formation is evidenced by C-13-NMR (and H-1-NMR) and by emission lifetime changes. In both solvents, supercomplex formation is complete in 1:1, 1.0 x 10(-4) M solutions, indicating very large stability constant values. A structure of the supercomplex with the macrocycle bound in a ''boat'' conformation to the four cyanide ligands of the complex, plausible in terms of molecular models, is consistent with all the experimental data. In water, the supercomplex further associates with added negative species containing carboxylate functions, as shown by partial reversal of the lifetime changes. When the added species is also a potential electron transfer quencher (such as, e.g., Rh(dcb)(3)(3-), dcb = 4,4'-dicarboxy-2,2'-bipyridine), however, association is not accompanied by quenching. This behavior is attributed to the structure of the supercomplex-quencher adduct, in which the macrocycle acts as an insulating spacer between the excited complex and the quencher.
ISI Document Delivery No.: UM693Times Cited: 44 Cited Reference Count: 32 Rampi, MA Indelli, MT Scandola, F Pina, F Parola, AJ Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Amer chemical soc Washington

Dielectric Studies on the miscibility in poly(vinyl acette)/poly(ethyl methacrylate) blends - M. Dionísio; J. J. Moura Ramos; A. Fernandes (Journal of Applied Polymer Science, 1996)

A Method for the Ventricular Late Potentials Detection and Characterisation using Wavelets - A.G., B; English, MJ (IEEE Engineering in Medicine and Biology Society, 1996)
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Molecular Motions in a Molecular Crystal: Tetrachloro-rn-Xylene - J. J. Moura Ramos; R. J. Cândido Sousa; N. T. Correia; M. Dionísio (Berichte der Bunsengesellschaft für physikalische Chemie, 1996)

A Multiresolution Wavelet Method for Charaterization of Ventricular Late Potentials - Batista, A.G.; English, MJ (Computers in Cardiology, 1996)
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NMR Studies of Cooperativity in the Tetrahaem Cytochrome c3 from Desulfovibrio vulgaris - Turner, David L.; Salgueiro, C.A.; Catarino, Teresa; Legall, Jean; Xavier, António V. (European Journal of Biochemistry, 1996)
The thermodynamic properties of the Desulfovibrio vulgaris (Hildenborough) tetrahaem cytochrome c3 (Dvc3) are rationalised by a model which involves both homotropic (e−/e−) and heterotropic (e−/H+) cooperativity. The paramagnetic shifts of a methyl group from each haem of the DVc3 have been determined in each stage of oxidation at several pH values by means of two-dimensional exchange NMR. The thermodynamic parameters are obtained by fitting the model to the NMR data and to redox titrations followed by visible spectroscopy. They show significant positive cooperativity between two of the haems whereas the remaining interactions appear to be largely electrostatic in origin. These parameters imply that the protein undergoes a proton-assisted two-electron transfer which can be used for energy transduction. Comparison with the crystal structure together with measurement of the kinetics of proton exchange suggest that the pH dependence is mediated by a charged residue(s) readily acessible to the solvent and close to haem I.

Redox-Bohr effect in the tetrahaem cytochrome c3 from Desulfovibrio vulgaris: a model for energy transduction mechanisms - Ricardo O. Louro; Catarino, Teresa; Salgueiro, C.A.; Legall, Jean; Xavier, António V. (Journal of Biological Inorganic Chemistry, 1996)
Using potentiometric titrations, two protons were found to participate in the redox-Bohr effect observed for cytochrome c3 from Desulfovibrio vulgaris (Hildenborough). Within the framework of the thermodynamic model previously presented, this finding supports the occurrence of a concerted proton-assisted 2e– step, ideally suited for the coupling role of cytochrome c3 to hydrogenase. Furthermore, at physiological pH, it is shown that when sulfate-reducing bacteria use H2 as energy source, cytochrome c3 can be used as a charge separation device, achieving energy transduction by energising protons which can be left in the acidic periplasmic side and transferring deenergised electrons to sulfate respiration. This mechanism for energy transduction, using a full thermodynamic data set, is compared to that put forward to explain the proton-pumping function of cytochrome c oxidase.

Site-directed mutagenesis of a phenylalanine residue strictly conserved in cytochromes c3 - Saraiva, Lígia M.; Salgueiro, C.A.; Legall, Jean; van Dongen, Walter M. A. M.; Xavier, António V. (Journal of Biological Inorganic Chemistry, 1996)
Reduction of the haems in tetrahaem cytochromes c3 is a cooperative process, i.e., reduction of each of the haems depends on the redox states of the other haems. Furthermore, electron transfer is coupled to proton transfer (redox-Bohr effect). Two of its haems and a strictly conserved nearby phenylalanine residue, F20, in Desulfovibrio vulgaris (Hildenborough) cytochrome c3 form a structural motif that is present in all cytochromes c3 and also in cytochrome c oxidase. A putative role for this phenylalanine residue in the cooperativity of haem reduction was investigated. Therefore, this phenylalanine was replaced, with genetic techniques, by isoleucine and tyrosine in D. vulgaris (Hildenborough) cytochrome c3. Cyclic voltammetry studies revealed a small increase (30 mV) in one of the macroscopic redox potentials in the mutated cytochromes. EPR showed that the main alterations occurred in the vicinity of haem I, the haem closest to residue 20 and one of the haems responsible for positive cooperativities in electron transfer of D. vulgaris cytochrome c3. NMR studies of F20I cytochrome c3 demonstrated that the haem core architecture is maintained and that the more affected haem proton groups are those near the mutation site. NMR redox titrations of this mutated protein gave evidence for only small changes in the relative redox potentials of the haems. However, electron/electron and proton/electron cooperativity are maintained, indicating that this aromatic residue has no essential role in these processes. Furthermore, chemical modification of the N-terminal amino group of cytochrome c3 backbone, which is also very close to haem I, had no effect on the network of cooperativities.

Analysis, design and engineering of simple iron-sulfur proteins: Tales from rubredoxin and desulforedoxin - Moura, J. J. G.; Goodfellow, B. J.; Romao, M. J.; Rusnak, F.; Moura, I. (Comments on Inorganic Chemistry, 1996)
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Times Cited: 10 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; A 10

Characterization of representative enzymes from a sulfate reducing bacterium implicated in the corrosion of steel - Pereira, A. S.; Franco, R.; Feio, M. J.; Pinto, C.; Lampreia, J.; Reis, M. A.; Calvete, J.; Moura, I.; Beech, I.; Lino, A. R.; Moura, J. J. G. (Biochemical And Biophysical Research Communications, 1996)
This communication reports the isolation, purification and characterization of key enzymes involved in dissimilatory sulfate reduction of a sulfate reducing bacterium classified as Desulfovibrio desulfuricans subspecies desulfuricans New Jersey (NCIMB 8313) (Ddd NJ). The chosen strain, originally recovered from a corroding cast iron heat exchanger, was grown in large scale batch cultures. Physico-chemical and spectroscopic studies of the purified enzymes were carried out. These analyses revealed a high degree of similarity between proteins isolated from the DddNJ strain and the homologous proteins obtained from Desulfomicrobium baculatus Norway 4. In view of the results obtained, taxonomic reclassification of Desulfovibrio desulfuricans subspecies desulfuricans New Jersey (NCIMB 8313) into Desulfomicrobium baculatus (New Jersey) is proposed. (C) 1996 Academic Press, Inc.
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Crystal structure of flavodoxin from Desulfovibrio desulfuricans ATCC 27774 in two oxidation states - Romero, A.; Caldeira, J.; Legall, J.; Moura, I.; Moura, J. J. G.; Romao, M. J. (European Journal of Biochemistry, 1996)
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Times Cited: 31 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; 32

Crystallographic and fluorescence studies of ligand binding to N-carbamoylsarcosine amidohydrolase from Arthrobacter sp - Zajc, A.; Romao, M. J.; Turk, B.; Huber, R. (Journal of Molecular Biology, 1996)
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Times Cited: 18 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 20

Long-range adaptive control algorithms for robotics applications - Lemos, J. M.; Coito, F.; Shirley, P.; Conceição, P.; Garcia, F.; Silvestre, C.; Sentieiro, J. (Progress in robotics and intelligent systems, 1996)
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A Method for the Ventricular Late Potentials Detection and Characterisation using Wavelets - Batista A.G.; English, MJ (IEEE Engineering in Medicine and Biology Society, 1996)
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A Multiresolution Wavelet Method for Charaterization of Ventricular Late Potentials - Batista, A.G.; English, MJ (Computers in Cardiology, 1996)
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Organizational alternatives for flexible manufacturing systems - António Moniz (University Library of Munich, Germany, 1996)
There is an increasing importance of different productive architectures related to worker involvement in the decision making, where is given due attention to the intuitive capabilities and the human knowledge in the optimization and flexibilization of manufacturing processes. Thus having reference point architecture of a flexible manufacturing and assembling system existent at UNINOVA-CRI, we will present some exploratory hypothesis about applicability of the concept of hybridization and its repercussions on the definition of jobs, in those organizations and in the formation of working teams.
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Keywords: flexibility; manufacturing industry; robotics; work organization

Primary structure of desulfoferrodoxin from Desulfovibrio desulfuricans ATCC 27774, a new class of non-heme iron proteins - Devreese, B.; Tavares, P; Lampreia, J.; Van Damme, N.; Legall, J.; Moura, J. J. G.; Van Beeumen, J.; Moura, I. (FEBS Letters, 1996)
The primary structure of desulfoferrodoxin from Desulfovibrio desulfuricans ATCC 27774, a redox protein with two mononuclear iron sites, was determined by automatic Edman degradation and mass spectrometry of the composing peptides, It contains 125 amino acid residues of which five are cysteines, The first four, Cys-9, Cys-12, Cys-28 and Cys-29, are responsible for the binding of Center I which has a distorted tetrahedral sulfur coordination similar to that found in desulforedoxin from D. gigas, The remaining Cys-115 is proposed to be involved in the coordination of Center II, which is probably octahedrally coordinated with predominantly nitrogen/oxygen containing ligands as previously suggested by Mossbauer and Raman spectroscopy.
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Protein-crystal density by volume measurement and amino-acid analysis - Kiefersauer, R.; Stetefeld, J.; GomisRuth, F. X.; Romao, M. J.; Lottspeich, F.; Huber, R. (Journal of Applied Crystallography, 1996)
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Times Cited: 12 Romao, Maria/A-4115-2013; REQUIMTE, SMB/M-5694-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; 4 12

Shape of acid-base fluorescence emission titration curves in the presence of buffer and quenching effects - Melo, MJ; Bernardo, M. A.; Melo, EC; Pina, F (Journal of the Chemical Society-Faraday Transactions, 1996)
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Times Cited: 14 Melo, Eurico/C-1297-2008; Melo, Maria Joao/C-8594-2011; Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Melo, Maria Joao/0000-0001-7393-6801; Pina, Fernando/0000-0001-8529-6848; 14

The solution structure of desulforedoxin, a simple iron-sulfur protein - An NMR study of the zinc derivative - Goodfellow, B. J.; Tavares, P; Romao, M. J.; Czaja, C.; Rusnak, F.; Legall, J.; Moura, I.; Moura, J. J. G. (Journal of Biological Inorganic Chemistry, 1996)
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Times Cited: 13 Romao, Maria/A-4115-2013; Moura, Jose/D-6426-2013; Pedro, Tavares/B-3654-2008; REQUIMTE, SMB/M-5694-2013; Moura, Isabel/D-6339-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; Pedro, Tavares/0000-0002-7398-2661; Moura, Isabel/0000-0003-0971-4977; 14

A structure-based catalytic mechanism for the xanthine oxidase family of molybdenum enzymes - Huber, R.; Hof, P.; Duarte, R. O.; Moura, J. J. G.; Moura, I.; Liu, M. Y.; Legall, J.; Hille, R.; Archer, M.; Romao, M. J. (Proceedings of the National Academy of Sciences of the United States of America, 1996)
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Times Cited: 194 Romao, Maria/A-4115-2013; Moura, Jose/D-6426-2013; Szaleniec, Maciej/A-1198-2013; 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; 200

Thermodynamic, NMR and photochemical study on the acid-base behaviour of N,N'-dibenzylated polyamines and on their interaction with hexacyanocobaltate(III) - Bernardo, M. A.; Guerrero, J. A.; Garciaespana, E.; Luis, SV; Llinares, J. M.; Pina, F; Ramirez, J. A.; Soriano, C (Journal of the Chemical Society-Perkin Transactions 2, 1996)
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Times Cited: 26 Pina, Fernando/C-8161-2011; REQUIMTE, PHOTO/M-4229-2013; REQUIMTE, LAQV/N-9835-2013 Pina, Fernando/0000-0001-8529-6848; 26

{Organizational alternatives for flexible manufacturing systems} - António Moniz (University Library of Munich, Germany, 1996)
There is an increasing importance of different productive architectures related to worker involvement in the decision making, where is given due attention to the intuitive capabilities and the human knowledge in the optimization and flexibilization of manufacturing processes. Thus having reference point architecture of a flexible manufacturing and assembling system existent at UNINOVA-CRI, we will present some exploratory hypothesis about applicability of the concept of hybridization and its repercussions on the definition of jobs, in those organizations and in the formation of working teams.
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Keywords: flexibility; manufacturing industry; robotics; work organization

Crystal structure of desulforedoxin from Desulfovibrio gigas determined at 1.8 A resolution: a novel non-heme iron protein structure - Archer, M.; Huber, R.; Tavares, P; Moura, I.; Moura, J. J.; Carrondo, M. A.; Sieker, L. C.; Legall, J.; Romao, M. J. (J Mol Biol, 1995)
The crystal structure of desulforedoxin from Desulfovibrio gigas, a new homo-dimeric (2 x 36 amino acids) non-heme iron protein, has been solved by the SIRAS method using the indium-substituted protein as the single derivative. The structure was refined to a crystallographic R-factor of 16.9% at 1.8 A resolution. Native desulforedoxin crystals were grown from either PEG 4K or lithium sulfate, with cell constants a = b = 42.18 A, c = 72.22 A (for crystals grown from PEG 4K), and they belong to space group P3(2)21. The indium-substituted protein crystallized isomorphously under the same conditions. The 2-fold symmetric dimer is firmly hydrogen bonded and folds as an incomplete beta-barrel with the two iron centers placed on opposite poles of the molecule. Each iron atom is coordinated to four cysteinyl residues in a distorted tetrahedral arrangement. Both iron atoms are 16 A apart but connected across the 2-fold axis by 14 covalent bonds along the polypeptide chain plus two hydrogen bonds. Desulforedoxin and rubredoxin share some structural features but show significant differences in terms of metal environment and water structure, which account for the known spectroscopic differences between rubredoxin and desulforedoxin.
0022-2836 (Print)0022-2836 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Amino Acid Sequence; Bacterial Proteins/*chemistry; Computer Graphics; Crystallography, X-Ray; Cysteine/chemistry; Desulfovibrio/*chemistry; Indium/chemistry; Iron-Sulfur Proteins/*chemistry; Iron/chemistry; Models, Molecular; Molecular Sequence Data; Molecular Structure; Protein Structure, Secondary; Rubredoxins/chemistry; Sequence Alignment; Water/metabolism

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.; Moura, I.; Rusnak, F. (J Biol Chem, 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.
0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Amino Acid Sequence; Amino Acids/analysis; Bacterial Proteins/biosynthesis; Base Sequence; Binding Sites; Cloning, Molecular; Desulfovibrio/genetics/*metabolism; DNA Primers; Electron Spin Resonance Spectroscopy/methods; Escherichia coli; Genes, Bacterial; Iron-Sulfur Proteins/*biosynthesis/*chemistry/isolation & purification; Iron/analysis/*metabolism; Mass Spectrometry; Molecular Sequence Data; Polymerase Chain Reaction; Protein Structure, Tertiary; Recombinant Proteins/biosynthesis/chemistry/isolation & purification; Spectrophotometry

Structure of the tetraheme cytochrome from Desulfovibrio desulfuricans ATCC 27774: X-ray diffraction and electron paramagnetic resonance studies - Morais, J.; Palma, P. N.; Frazao, C.; Caldeira, J.; Legall, J.; Moura, I.; Moura, J. J.; Carrondo, M. A. (Biochemistry, 1995)
The three-dimensional X-ray structure of cytochrome c3 from a sulfate reducing bacterium, Desulfovibrio desulfuricans ATCC 27774 (107 residues, 4 heme groups), has been determined by the method of molecular replacement [Frazao et al. (1994) Acta Crystallogr. D50, 233-236] and refined at 1.75 A to an R-factor of 17.8%. When compared with the homologous proteins isolated from Desulfovibrio gigas, Desulfovibrio vulgaris Hildenborough, Desulfovibrio vulgaris Miyazaki F, and Desulfomicrobium baculatus, the general outlines of the structure are essentialy kept [heme-heme distances, heme-heme angles, His-His (axial heme ligands) dihedral angles, and the geometry of the conserved aromatic residues]. The three-dimensional structure of D. desulfuricans ATCC 27774 cytochrome c3Dd was modeled on the basis of the crystal structures available and amino acid sequence comparisons within this homologous family of multiheme cytochromes [Palma et al. (1994) Biochemistry 33, 6394-6407]. This model is compared with the refined crystal structure now reported, in order to discuss the validity of structure prediction methods and critically evaluate the steps used to predict protein structures by homology modeling. The four heme midpoint redox potentials were determined by using deconvoluted electron paramagnetic resonance (EPR) redox titrations. Structural criteria (electrostatic potentials, heme ligand orientation, EPR g values, heme exposure, data from protein-protein interaction studies) are invoked to assign the redox potentials corresponding to each specific heme in the three-dimensional structure.
0006-2960 (Print)0006-2960 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Crystallography, X-Ray; Cytochrome c Group/*chemistry; Desulfovibrio/*enzymology; Electron Spin Resonance Spectroscopy; Hydrogen Bonding; Models, Molecular; Oxidation-Reduction; Protein Conformation

Resonance Raman study on the iron-sulfur centers of Desulfovibrio gigas aldehyde oxidoreductase - Zhelyaskov, V.; Yue, K. T.; Legall, J.; Barata, B. A.; Moura, J. J. (Biochim Biophys Acta, 1995)
Resonance Raman spectra of the molybdenum containing aldehyde oxidoreductase from Desulfovibrio gigas were recorded at liquid nitrogen temperature with various excitation wavelengths. The spectra indicate that all the iron atoms are organised in [2Fe-2S] type centers consistent with cysteine ligations. No vibrational modes involving molybdenum could be clearly identified. The features between 280 and 420 cm-1 are similar but different from those of typical plant ferredoxin-like [2Fe-2S] cluster. The data are consistent with the presence of a plant ferredoxin-like cluster (center I) and a unique [2Fe-2S] cluster (center II), as suggested by other spectroscopic studies. The Raman features of center II are different from those of other [2Fe-2S] clusters in proteins. In addition, a strong peak at ca. 683 cm-1, which is not present in other [2Fe-2S] clusters in proteins, was observed with purple excitation (406.7-413.1 nm). The peak is assigned to enhanced cysteinyl C-S stretching in center II, suggesting a novel geometry for this center.
0006-3002 (Print)0006-3002 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Aldehyde Oxidoreductases/*chemistry; Desulfovibrio/*enzymology; Iron-Sulfur Proteins/*analysis; Molybdenum; Plants/enzymology; Spectrum Analysis, Raman

Mossbauer characterization of Paracoccus denitrificans cytochrome c peroxidase. Further evidence for redox and calcium binding-induced heme-heme interaction - Prazeres, S.; Moura, J. J.; Moura, I.; Gilmour, R.; Goodhew, C. F.; Pettigrew, G. W.; Ravi, N.; Huynh, B. H. (J Biol Chem, 1995)
Mossbauer and electron paramagnetic resonance (EPR) spectroscopies were used to characterize the diheme cytochrome c peroxidase from Paracoccus denitrificans (L.M.D. 52.44). The spectra of the oxidized enzyme show two distinct spectral components characteristic of low spin ferric hemes (S = 1/2), revealing different heme environments for the two heme groups. The Paracoccus peroxidase can be non-physiologically reduced by ascorbate. Mossbauer investigation of the ascorbate-reduced peroxidase shows that only one heme (the high potential heme) is reduced and that the reduced heme is diamagnetic (S = 0). The other heme (the low potential heme) remains oxidized, indicating that the enzyme is in a mixed valence, half-reduced state. The EPR spectrum of the half-reduced peroxidase, however, shows two low spin ferric species with gmax = 2.89 (species I) and gmax = 2.78 (species II). This EPR observation, together with the Mossbauer result, suggests that both species are arising from the low potential heme. More interestingly, the spectroscopic properties of these two species are distinct from that of the low potential heme in the oxidized enzyme, providing evidence for heme-heme interaction induced by the reduction of the high potential heme. Addition of calcium ions to the half-reduced enzyme converts species II to species I. Since calcium has been found to promote peroxidase activity, species I may represent the active form of the peroxidatic heme.
0021-9258 (Print)0021-9258 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.
Keywords: Animals; Calcium/*metabolism/pharmacology; Cytochrome-c Peroxidase/*chemistry/metabolism; Electron Spin Resonance Spectroscopy/methods; Heme/*chemistry/metabolism; Hemeproteins/*chemistry; Least-Squares Analysis; Models, Structural; Oxidation-Reduction; Paracoccus denitrificans/*enzymology; Protein Conformation; Spectroscopy, Mossbauer/methods

Characterization of the iron-binding site in mammalian ferrochelatase by kinetic and Mossbauer methods - Franco, R.; Moura, J. J.; Moura, I.; Lloyd, S. G.; Huynh, B. H.; Forbes, W. S.; Ferreira, G. C. (J Biol Chem, 1995)
All organisms utilize ferrochelatase (protoheme ferrolyase, EC 4.99.1.1) to catalyze the terminal step of the heme biosynthetic pathway, which involves the insertion of ferrous ion into protoporphyrin IX. Kinetic methods and Mossbauer spectroscopy have been used in an effort to characterize the ferrous ion-binding active site of recombinant murine ferrochelatase. The kinetic studies indicate that dithiothreitol, a reducing agent commonly used in ferrochelatase activity assays, interferes with the enzymatic production of heme. Ferrochelatase specific activity values determined under strictly anaerobic conditions are much greater than those obtained for the same enzyme under aerobic conditions and in the presence of dithiothreitol. Mossbauer spectroscopy conclusively demonstrates that, under the commonly used assay conditions, dithiothreitol chelates ferrous ion and hence competes with the enzyme for binding the ferrous substrate. Mossbauer spectroscopy of ferrous ion incubated with ferrochelatase in the absence of dithiothreitol shows a somewhat broad quadrupole doublet. Spectral analysis indicates that when 0.1 mM Fe(II) is added to 1.75 mM ferrochelatase, the overwhelming majority of the added ferrous ion is bound to the protein. The spectroscopic parameters for this bound species are delta = 1.36 +/- 0.03 mm/s and delta EQ = 3.04 +/- 0.06 mm/s, distinct from the larger delta EQ of a control sample of Fe(II) in buffer only. The parameters for the bound species are consistent with an active site composed of nitrogenous/oxygenous ligands and inconsistent with the presence of sulfur ligands. This finding is in accord with the absence of conserved cysteines among the known ferrochelatase sequences. The implications these results have with regard to the mechanism of ferrochelatase activity 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: Animals; Binding Sites; Cloning, Molecular; Dithiothreitol/metabolism; Escherichia coli; Ferrochelatase/*chemistry/isolation & purification/*metabolism; Hydrogen-Ion Concentration; Iron/*metabolism; Kinetics; Liver/enzymology; Mammals; Mathematics; Mice; Models, Theoretical; Protoporphyrins/pharmacology; Recombinant Proteins/chemistry/isolation & purification/metabolism; Spectroscopy, Mossbauer/methods

Crystal structure of the xanthine oxidase-related aldehyde oxido-reductase from D. gigas - Romao, M. J.; Archer, M.; Moura, I.; Moura, J. J.; Legall, J.; Engh, R.; Schneider, M.; Hof, P.; Huber, R. (Science, 1995)
The crystal structure of the aldehyde oxido-reductase (Mop) from the sulfate reducing anaerobic Gram-negative bacterium Desulfovibrio gigas has been determined at 2.25 A resolution by multiple isomorphous replacement and refined. The protein, a homodimer of 907 amino acid residues subunits, is a member of the xanthine oxidase family. The protein contains a molybdopterin cofactor (Mo-co) and two different [2Fe-2S] centers. It is folded into four domains of which the first two bind the iron sulfur centers and the last two are involved in Mo-co binding. Mo-co is a molybdenum molybdopterin cytosine dinucleotide. Molybdopterin forms a tricyclic system with the pterin bicycle annealed to a pyran ring. The molybdopterin dinucleotide is deeply buried in the protein. The cis-dithiolene group of the pyran ring binds the molybdenum, which is coordinated by three more (oxygen) ligands.
0036-8075 (Print)0036-8075 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Aldehyde Oxidoreductases/*chemistry/metabolism; Amino Acid Sequence; Animals; Coenzymes/chemistry/metabolism; Crystallization; Crystallography, X-Ray; Cytosine Nucleotides/chemistry/metabolism; Desulfovibrio/*enzymology; Drosophila melanogaster/enzymology; Electron Transport; Hydrogen Bonding; Iron/chemistry; Ligands; Metalloproteins/chemistry/metabolism; Molecular Sequence Data; Molybdenum/chemistry/metabolism; Oxidation-Reduction; Protein Conformation; Protein Folding; Protein Structure, Secondary; Pteridines/chemistry/metabolism; Pterins/chemistry/metabolism; Xanthine; Xanthine Oxidase/*chemistry; Xanthines/metabolism

Total synthesis of a simple metalloprotein-desulforedoxin - Tavares, P; Wunderlich, J. K.; Lloyd, S. G.; Legall, J.; Moura, J. J.; Moura, I. (Biochem Biophys Res Commun, 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 Dx are very similar, in terms redox potential and spectroscopic properties (UV-Visible, EPR, Mossbauer).
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Cysteine/chemistry; Desulfovibrio/chemistry; Electron Spin Resonance Spectroscopy; Iron-Sulfur Proteins/*chemical synthesis; Spectrophotometry, Ultraviolet; Spectrum Analysis

Characterization of the interaction between PQQ and heme c in the quinohemoprotein ethanol dehydrogenase from Comamonas testosteroni - de Jong, G. A.; Caldeira, J.; Sun, J.; Jongejan, J. A.; de Vries, S.; Loehr, T. M.; Moura, I.; Moura, J. J.; Duine, J. A. (Biochemistry, 1995)
Quinohemoprotein ethanol dehydrogenase from Comamonas testosteroni (QH-EDH) contains two cofactors, 2,7,9-tricarboxy-1H-pyrrolo[2,3-f]quinoline-4,5-dione (PQQ) and heme c. Since previous studies on the kinetics of this enzyme suggested that both participate in electron transfer, spectroscopic investigations were performed of the oxidized and reduced holo- and apoenzyme (without PQQ but with heme c) to reveal the nature of the interaction between the two redox centers. From this it appears that the properties of the heme in the enzyme are affected by the presence of PQQ, as judged from the shift of the maxima in the ultraviolet/visible absorption spectra of the heme moiety in both reduced and oxidized QH-EDH and the 60-mV increase of the heme midpoint redox potential caused by PQQ addition. Also 1H-NMR spectroscopy was indicative for interaction since binding of PQQ induced shifts in the resonances of the methyl groups of the porphyrin ring in the oxidized form of the apoenzyme and a shift in the methionine heme ligand resonance of the reduced form of the apoenzyme. On the other hand, resonance Raman spectra of the heme in the different enzyme forms were nearly similar. These results suggest that a major effect of PQQ binding to apo-QH-EDH is a rotation of the methionine ligand of heme c. Since no intermediate 1H-NMR spectra were observed upon titration of apoenzyme with PQQ, apparently no exchange occurs of PQQ between (oxidized) holo- and apoenzyme at the NMR time scale and at that of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)
0006-2960 (Print)0006-2960 (Linking)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov't
Keywords: Alcohol Oxidoreductases/*chemistry/*metabolism; Apoenzymes/chemistry/metabolism; Coenzymes/metabolism; Gram-Negative Aerobic Bacteria/*enzymology; Heme/*analogs & derivatives/metabolism; Kinetics; Magnetic Resonance Spectroscopy; Oxidation-Reduction; PQQ Cofactor; Protein Binding; Protein Conformation; Quinolones/*metabolism; Spectrophotometry; Spectrum Analysis, Raman

Metabolic adaptations induced by long-term fasting in quails - Sartori, D. R.; Migliorini, R. H.; Veiga, J. A.; Moura, J. L.; Kettelhut, I. C.; Linder, C. (Comp Biochem Physiol A Physiol, 1995)
After up to 21 days without food, adult male quails (Coturnix coturnix japonica) lost about 45% of the initial body weight (100-150 g). As in naturally fast-adapted and larger birds, three phases were identified during prolonged fasting in quails. Phase I lasted 2-3 days and was characterized by a rapid decrease in the rate of body weight loss and high fat mobilization. Phase II was longer and characterized by a slow and steady decline in the rates of body weight loss and of nitrogen excretion. The third (critical) period was marked by an abrupt increase in the rates of body weight loss and of nitrogen excretion. Despite their small size, the duration of phase II in quails was relatively long, a clear advantage for the study of the relationships between the several metabolic events that occur during this crucial adaptative period. Also, the beginning of phase III could be precisely determined. Changes in blood glucose, plasma FFA and triacylglycerols levels, as well as in liver and carcass lipid content were similar to those found in other species of birds. Therefore, quails seem to be a suitable model to investigate the biochemical mechanisms involved in the metabolic adjustments to prolonged food deprivation in non fasting-adapted birds.
1096-4940 (Print)1096-4940 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Adaptation, Physiological/*physiology; Amino Acids/blood; Animals; Blood Glucose/metabolism; Body Weight/physiology; Coturnix/*metabolism; Dietary Carbohydrates/metabolism; Dietary Proteins/metabolism; Fasting/*metabolism; Fatty Acids, Nonesterified/blood; Lipid Metabolism; Lipids/blood; Liver/metabolism; Male; Nitrogen/urine; Triglycerides/blood

Isolation and preliminary characterization of a soluble nitrate reductase from the sulfate reducing organism Desulfovibrio desulfuricans ATCC 27774 - Bursakov, S.; Liu, M. Y.; Payne, W. J.; Legall, J.; Moura, I.; Moura, J. J. (Anaerobe, 1995)
Desulfovibrio desulfuricans ATCC 27774 is a sulfate reducer that can adapt to nitrate respiration, inducing the enzymes required to utilize this alternative metabolic pathway. Nitrite reductase from this organism has been previously isolated and characterized, but no information was available on the enzyme involved in the reduction of nitrate. This is the first report of purification to homogeneity of a nitrate reductase from a sulfate reducing organism, thus completing the enzymatic system required to convert nitrate (through nitrite) to ammonia. D. desulfuricans nitrate reductase is a monomeric (circa 70 kDa) periplasmic enzyme with a specific activity of 5.4 K(m) for nitrate was estimated to be 20 microM. EPR signals due to one [4Fe-4S] cluster and Mo(V) were identified in dithionite reduced samples and in the presence of nitrate.
1075-9964 (Print)1075-9964 (Linking)Journal Article

The affinity and specificity of Ca(2+)-binding sites of cytochrome-c peroxidase from Paracoccus denitrificans - Gilmour, R.; Prazeres, S.; McGinnity, D. F.; Goodhew, C. F.; Moura, J. J.; Moura, I.; Pettigrew, G. W. (Eur J Biochem, 1995)
The binding of Ca2+ to the dihaem cytochrome-c peroxidase from Paracoccus denitrificans was analysed by following perturbations in the visible and 1H-NMR spectra of both haem groups. The enzyme contains at least two types of Ca(2+)-binding site. Site I is occupied in the isolated enzyme, binds Ca2+ with a redox-state-independent Kd of 1.2 microM and accommodates neither Mg2+ nor Mn2+. Site II is unoccupied in dilute solutions of the isolated oxidised enzyme and binds Ca2+ cooperatively with a Kd of 0.52 mM. In the mixed valence form, the binding affinity increases to resemble that of site I. The cooperativity was shown by -Ca2+ binding to site II, the titration of haem methyl 1H-NMR resonances, and a half-of-sites effect observed for modification of an essential histidine with diethylpyrocarbonate. These are all consistent with site II being situated at the interface between two monomers of a dimeric enzyme. Thus the equilibrium of binding to site II is a reflection of the equilibrium for dimerisation and conditions which shift that equilibrium towards the dimer, such as increased ionic strength or high protein concentration, also increase Ca2+ affinity. Binding of Ca2+ to site II is required for formation of the active high spin state at the peroxidatic haem.
0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't
Keywords: Ascorbic Acid/pharmacology; Binding Sites; Calcium/*metabolism/pharmacology; Cytochrome-c Peroxidase/*chemistry/metabolism; Edetic Acid/pharmacology; Egtazic Acid/pharmacology; Magnesium/metabolism; Magnetic Resonance Spectroscopy; Manganese/metabolism; Models, Chemical; Oxidation-Reduction; Paracoccus denitrificans/*enzymology; Protein Binding; Protein Conformation; Spectrophotometry; Substrate Specificity; Titrimetry

A cytochrome cd1-type nitrite reductase isolated from the marine denitrifier Pseudomonas nautica 617: purification and characterization - Besson, S.; Carneiro, C.; Moura, J. J.; Moura, I.; Fauque, G. (Anaerobe, 1995)
Nitrite reductase (cytochrome cd1) was purified to electrophoretic homogeneity from the soluble extract of the marine denitrifying bacterium Pseudomonas nautica strain 617. Cells were anaerobically grown with 10 mM nitrate as final electron acceptor. The soluble fraction was purified by four successive chromatographic steps and the purest cytochrome cd1 exhibited an A280 nm(oxidized)/A410nm(oxidized) coefficient of 0.90. In the course of purification, cytochrome cd1 specific activity presented a maximum value of 0.048 units/mg of protein. This periplasmic enzyme is a homodimer and each 60 kDa subunit contains one heme c and one heme d1 as prosthetic moieties, both in a low spin state. Redox potentials of hemes c and d1 were determined at three different pH values (6.6, 7.6 and 8.6) and did not show any pH dependence. The first 20 amino acids of the NH2-terminal region of the protein were identified and the sequence showed 45% identity with the corresponding region of Pseudomonas aeruginosa nitrite reductase but no homology to Pseudomonas stutzeri and Paracoccus denitrificans enzymes. Spectroscopic properties of Pseudomonas nautica 617 cytochrome cd1 in the ultraviolet-visible range and in electron paramagnetic resonance are described. The formation of a heme d1 -nitric-oxide complex as an intermediate of nitrite reduction was demonstrated by electron paramagnetic resonance experiments.
1075-9964 (Print)1075-9964 (Linking)Journal Article

Electrochemical studies on nitrite reductase towards a biosensor - Scharf, M.; Moreno, C.; Costa, C.; Van Dijk, C.; Payne, W. J.; Legall, J.; Moura, I.; Moura, J. J. (Biochem Biophys Res Commun, 1995)
A c-type hexaheme nitrite reductase (NiR) isolated from nitrate-grown cells of Desulfovibrio desulfuricans (Dd) ATCC 27774 catalyses the six-electron reduction of nitrite to ammonia. Previous electrochemical studies demonstrated that a simple electrocatalytic mechanism can be applied to this system (Moreno, C., Costa, C., Moura, I., LeGall, J., Liu, M. Y., Payne, W. J., Van Dijk, C. and Moura, J. J. G. (1992) Eur.J.Biochem. 212, 79-86). Its substrate specificity, availability and stability under ambient conditions makes this enzymatic system a promising candidate for use in a biosensor device. An electrochemical study of gel-immobilized Dd NiR on a glassy carbon electrode revealed both enzymatic activity and amperometric response to nitrite. In this study it was observed that the catalytic current density is a function of the nitrite concentration in solution and follows a characteristic Michaelis-Menten-type substrate dependence. Such a biosensor device (NiR-electrode) bears the option to be used for analytical determination of nitrite in complex media.
0006-291X (Print)0006-291X (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.
Keywords: Biosensing Techniques; Desulfovibrio/*enzymology/growth & development; Electrochemistry/methods; Enzymes, Immobilized/analysis/*metabolism; Kinetics; Nitrite Reductases/analysis/*metabolism; Oxidation-Reduction; Potentiometry/methods

LOW-ENERGY TANDEM MASS-SPECTROMETRY OF DEOXYNUCLEOSIDE ADDUCTS OF POLYCYCLIC AROMATIC HYDROCARBON DIHYDRODIOL-EPOXIDES - Branco, P. S.; Chiarelli, MP; LAY, JO; BELAND, FA (JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY, 1995)
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Structure and function of ferrochelatase - Ferreira, G. C.; Franco, R.; Lloyd, S. G.; Moura, I.; Moura, J. J.; Huynh, B. H. (J Bioenerg Biomembr, 1995)
Ferrochelatase is the terminal enzyme of the heme biosynthetic pathway in all cells. It catalyzes the insertion of ferrous iron into protoporphyrin IX, yielding heme. In eukaryotic cells, ferrochelatase is a mitochondrial inner membrane-associated protein with the active site facing the matrix. Decreased values of ferrochelatase activity in all tissues are a characteristic of patients with protoporphyria. Point-mutations in the ferrochelatase gene have been recently found to be associated with certain cases of erythropoietic protoporphyria. During the past four years, there have been considerable advances in different aspects related to structure and function of ferrochelatase. Genomic and cDNA clones for bacteria, yeast, barley, mouse, and human ferrochelatase have been isolated and sequenced. Functional expression of yeast ferrochelatase in yeast strains deficient in this enzyme, and expression in Escherichia coli and in baculovirus-infected insect cells of different ferrochelatase cDNAs have been accomplished. A recently identified (2Fe-2S) cluster appears to be a structural feature shared among mammalian ferrochelatases. Finally, functional studies of ferrochelatase site-directed mutants, in which key amino acids were replaced with residues identified in some cases of protoporphyria, will be summarized in the context of protein structure.
0145-479X (Print)0145-479X (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; Animals; Cloning, Molecular; Ferrochelatase/*chemistry/genetics/*physiology; Heme/biosynthesis; Humans; Mice; Mitochondria/enzymology; Molecular Sequence Data; Molecular Structure; Mutagenesis, Site-Directed; Sequence Homology, Amino Acid

Control of the thermal and photochemical aquation of the hexacyanochromate(III) and aquapentacyanochromate(III) ions by formation of a supramolecular structure with 32 ane-N-8 - J. Sotomayor; A. J. Parola; Pina, F; Zinato, E.; Riccieri, P.; Manfrin, M. F.; Moggi, L. (Inorganic Chemistry, 1995)
The thermal aquation rate constant and the photoaquation quantum yield of [Cr(CN)(6)](3-) are reduced by a factor of 40 and 3, respectively, when the complex forms a 1:1 adduct with the protonated form of the polyaza macrocycle [32]ane-N-8. On the other hand, the same macrocycle has practically no effect on the photoaquation of [Cr(CN)(5)(H2O)](2-) and a very small effect on the thermal reaction of this complex. These results are discussed in relation to the thermal and photochemical reaction mechanisms and to the steric configuration of the adducts between complexes and macrocycle.
ISI Document Delivery No.: TM021Times Cited: 12 Cited Reference Count: 34 Sotomayor, J Parola, AJ Pina, F Zinato, E Riccieri, P Manfrin, MF Moggi, L Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010; Sotomayor, Joao/D-8103-2013 Parola, A. Jorge/0000-0002-1333-9076; Sotomayor, Joao/0000-0002-4589-0591 Amer chemical soc Washington

STEADY-STATE FLUORESCENCE EMISSION STUDIES ON POLYAZACYCLOPHANE MACROCYCLIC RECEPTORS AND ON THEIR ADDUCTS WITH HEXACYANOCOBALTATE(III) - Bernardo, M. A.; A. J. Parola; Pina, F; Garciaespana, E.; Marcelino, V.; Luis, SV; Miravet, J. F. (Journal of the Chemical Society-Dalton Transactions, 1995)
The steady-state fluorescence emission spectra of the azacyclophanes 2,5,8,11-tetraaza[12] paracyclophane (L(1)), 2,6,9,13-tetraaza[14]paracyclophane (L(2)), 14,15,17,18-tetramethyl-2,5,8,11-tetraaza-[12]paracyclophane (L(3)) and 16,17,19,20-tetramethyl-2,6,9,13-tetraaza[14]paracyclophane (L(4)) as a function of pH have been measured. The fully protonated species of each cyclophane gives the highest fluorescence-emission quantum yield. The shapes of the titration curves have been explained by the existence of an electron-transfer quenching effect from a non-protonated amine to the benzene chromophore. This effect is greater for macrocycles in which the first deprotonated amine group is closer to the benzene. The association constants for the interaction of the four fully protonated macrocycles with K-3[Co(CN)(6)] have been measured either by potentiometry or from fluorescence-emission measurements, and increase in the order L(3) approximate to L(4) < L(1) approximate to L(2). The photoaquation quantum yields of K-3[Co(CN)(6)] have been measured in the presence of the macrocycles L(1) and L(2). and indicate that three of the CN nitrogens of the complex are involved in adduct formation with the fully protonated macrocycles, as supported by molecular modelling.
ISI Document Delivery No.: QN860Times Cited: 29 Cited Reference Count: 27 Bernardo, ma parola, aj pina, f garciaespana, e marcelino, v luis, sv miravet, jf Pina, Fernando/C-8161-2011; Parola, A. Jorge/F-4048-2010 Parola, A. Jorge/0000-0002-1333-9076 Royal soc chemistry Cambridge

SUPRAMOLECULAR PHOTOCHEMISTRY AND PHOTOPHYSICS - BIACETYL IMPRISONED IN A HEMICARCERAND - Pina, F; A. J. Parola; Ferreira, E.; Maestri, M; Armaroli, N.; Ballardini, R; Balzani, V. (Journal of Physical Chemistry, 1995)
When biacetyl is imprisoned into Cram's hemicarcerand 1, its absorption, fluorescence, and phosphorescence maxima are red shifted compared to the values obtained for solutions of free biacetyl in any solvent. Furthermore, the lifetime of the T-1 excited state of imprisoned biacetyl is unaffected by solvent nature and presence of dioxygen. These results show that inclusion into the hemicarcerand (i) shields biacetyl from interaction with the solvent molecules and (ii) prevents deactivation of its long-lived T-1 excited state by energy transfer to dioxygen. The perturbation provided by the cavity on the spectroscopic properties of biacetyl is much smaller than that provided by even the most ''innocent'' solvent. The consequent picture is that of a biacetyl molecule which is contained in a not-too-tight cavity where no specific host-guest interaction takes place. The peculiar spectroscopic and excited-state behavior of biacetyl imprisoned in hemicarcerand 1 supports Cram's view that the inner phase of carcerands and hemicarcerands is to be considered as a new phase of matter.
ISI Document Delivery No.: RR250Times Cited: 34 Cited Reference Count: 20 Pina, f parola, aj ferreira, e maestri, m armaroli, n ballardini, r 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 Amer chemical soc Washington

Absorbed water in the cork structure. A study by thermally stimulated currents, dielectric relaxation spectroscopy, isothermal depolarization experiments and differential scanning calorimetry - M. Dionísio; N. T. Correia; J.F. Mano; J. J. Moura Ramos; A. C. Fernandes; Saramago, B. (Journal of Materials Science, 1995)

Carbon-13 NMR studies of the influence of axial ligand orientation on haem electronic structure - Turner, David L.; Salgueiro, C.A.; Schenkels, Peter; Legall, Jean; Xavier, António V. (Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1995)
Three-quarters of the carbon-13 resonances of nuclei attached to the four haems of Desulfovibrio vulgaris ferricytochrome c3 are assigned. Preliminary analysis of their Fermi contact interactions shows that the shifts are directly related to the orientation of both of the axial histidine ligands in each case and the approach can therefore be used to obtain structural information in other cytochromes with bis-histidinyl coordination. The implications for the control of redox potential in cytochromes are discussed.

Time-Frequency and Wavelet Analysis of the Beat-by-Beat High Resolution Electrocardiogram (Sussex University, 1995)
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Aplicações biológicas da espectroscopia de Mossbauer - Correlação com a espectroscopia de Ressonância Paramagnética Electrónica - Alguns exemplos ilustrativos - Moura, I. (Boletim da Sociedade Portuguesa de Biotecnologia, 1995)
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Co-pigmentation of anthocyanins through the formation of ion-pairs - FIGUEIREDO, P; Pina, F (Polyphenols 94, 1995)
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Times Cited: 0 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; 17th International Conference on Polyphenols May 23-27, 1994 Palma de mallorca, spain Grp Polyphenols

CRYSTAL-STRUCTURE OF DESULFOREDOXIN FROM DESULFOVIBRIO-GIGAS DETERMINED AT 1.8 ANGSTROM RESOLUTION - A NOVEL NONHEME IRON PROTEIN-STRUCTURE - Archer, M.; Huber, R.; Tavares, P; Moura, I.; Moura, J. J. G.; Carrondo, M. A.; Sieker, L. C.; Legall, J.; Romão, M.J. (JOURNAL OF MOLECULAR BIOLOGY, 1995)
The crystal structure of desulforedoxin from Desulfovibrio gigas, a new homo-dimeric (2x36 amino acids) non-heme iron protein, has been solved by the SIRAS method using the indium-substituted protein as the single derivative. The structure was refined to a crystallographic X-factor of 16.9% at 1.8 Angstrom resolution. Native desulforedoxin crystals were grown from either PEG 4K or lithium sulfate, with cell constants a = b = 42.18 Angstrom, = 72.22 Angstrom (for crystals grown from PEG 4K), and they belong to space group P3(2)21. The indium-substituted protein crystallized isomorphously under the same conditions. The 2-fold symmetric dimer is firmly hydrogen bonded and folds as an incomplete beta-barrel with the two iron centers placed on opposite poles of the molecule. Each iron atom is coordinated to four cysteinyl residues in a distorted tetrahedral arrangement. Both iron atoms are 16 Angstrom apart but connected across the 2-fold axis by 14 covalent bonds along the polypeptide chain plus two hydrogen bonds. Desulforedoxin and rubredoxin share some structural features but show significant differences in terms of metal environment and water structure, which account for the known spectroscopic differences between rubredoxin and desulforedoxin. (C) 1995 Academic Press Limited
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CRYSTAL-STRUCTURE OF DESULFOREDOXIN FROM DESULFOVIBRIO-GIGAS DETERMINED AT 1.8 ANGSTROM RESOLUTION - A NOVEL NONHEME IRON PROTEIN-STRUCTURE - Archer, M.; Huber, R.; Tavares, P; Moura, I.; Moura, J. J. G.; Carrondo, M. A.; Sieker, L. C.; Legall, J.; Romao, M. J. (Journal of Molecular Biology, 1995)
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Times Cited: 70 Romao, Maria/A-4115-2013; Moura, Jose/D-6426-2013; Pedro, Tavares/B-3654-2008; REQUIMTE, SMB/M-5694-2013; Moura, Isabel/D-6339-2013; REQUIMTE, UCIBIO/N-9846-2013 Romao, Maria/0000-0002-3004-0543; Pedro, Tavares/0000-0002-7398-2661; Moura, Isabel/0000-0003-0971-4977; 71

CRYSTAL-STRUCTURE OF THE XANTHINE OXIDASE-RELATED ALDEHYDE OXIDOREDUCTASE FROM D-GIGAS - Romao, M. J.; Archer, M.; Moura, I.; Moura, J. J. G.; Legall, J.; Engh, R.; Schneider, M.; Hof, P.; Huber, R. (Science, 1995)
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Times Cited: 371 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; 374