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1989
Eidsness, MK, Scott RA, Prickril BC, Dervartanian DV, Legall J, Moura I, Moura JJ, Peck, H. D. J.  1989.  Evidence for selenocysteine coordination to the active site nickel in the [NiFeSe]hydrogenases from Desulfovibrio baculatus, Jan. Proc Natl Acad Sci U S A. 86:147-51., Number 1 AbstractWebsite

Ni and Se x-ray absorption spectroscopic studies of the [NiFeSe]hydrogenases from Desulfovibrio baculatus are described. The Ni site geometry is pseudo-octahedral with a coordinating ligand composition of 3-4 (N,O) at 2.06 A, 1-2 (S,Cl) at 2.17 A, and 1 Se at 2.44 A. The Se coordination environment consists of 1 C at 2.0 A and a heavy scatterer M (M = Ni or Fe) at approximately 2.4 A. These results are interpreted in terms of a selenocysteine residue coordinated to the Ni site. The possible role of the Ni-Se site in the catalytic activation of H2 is discussed.

He, SH, Teixeira M, Legall J, Patil DS, Moura I, Moura JJ, Dervartanian DV, Huynh BH, Peck, H. D. J.  1989.  EPR studies with 77Se-enriched (NiFeSe) hydrogenase of Desulfovibrio baculatus. Evidence for a selenium ligand to the active site nickel, Feb 15. J Biol Chem. 264:2678-82., Number 5 AbstractWebsite

The periplasmic hydrogenase containing equivalent amounts of nickel and selenium plus non-heme iron [NiFeSe) hydrogenase) has been purified from cells of the sulfate reducing bacterium Desulfovibrio baculatus (DSM 1748) grown on a lactate/sulfate medium containing natural Se isotopes and the nuclear isotope, 77Se. Both the 77Se-enriched and unenriched hydrogenases were shown to be free of other hydrogenases and characterized with regard to their Se contents. EPR studies of the reduced nickel signal generated by redox titrations of the enriched and unenriched (NiFeSe) hydrogenases demonstrated that the gx = 2.23 and gy = 2.17 resonances are appreciably broadened by the spin of the 77Se nucleus (I = 1/2). This observation demonstrates unambiguously that the unpaired electron is shared by the Ni and Se atoms and that Se serves as a ligand to the nickel redox center of the (NiFeSe) hydrogenase.

Sotomayor, J, Costa JC, Mulazzani QG, Pina F.  1989.  PHOTODECARBOXYLATION OF CITRATE THROUGH ION-PAIR PHOTOCHEMISTRY - THE CO(SEP)3+CITRATE1-, CITRATE2-, CITRATE3- SYSTEM. Journal of Photochemistry and Photobiology a-Chemistry. 49:195-202., Number 1-2 AbstractWebsite
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Pina, F, Costa JC.  1989.  QUANTUM YIELD DETERMINATIONS ON THE CO(EDTA) -I-SYSTEM. Journal of Photochemistry and Photobiology a-Chemistry. 48:233-242., Number 2-3 AbstractWebsite
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1988
Moura, I, Teixeira M, Huynh BH, Legall J, Moura JJ.  1988.  Assignment of individual heme EPR signals of Desulfovibrio baculatus (strain 9974) tetraheme cytochrome c3. A redox equilibria study, Sep 15. Eur J Biochem. 176:365-9., Number 2 AbstractWebsite

An EPR redox titration was performed on the tetraheme cytochrome c3 isolated from Desulfovibrio baculatus (strain 9974), a sulfate-reducer. Using spectral differences at different poised redox states of the protein, it was possible to individualize the EPR g-values of each of the four hemes and also to determine the mid-point redox potentials of each individual heme: heme 4 (-70 mV) at gmax = 2.93, gmed = 2.26 and gmin = 1.51; heme 3 (-280 mV) at gmax = 3.41; heme 2 (-300 mV) at gmax = 3.05, gmed = 2.24 and gmin = 1.34; and heme 1 (-355 mV) at gmx = 3.18. A previously described multi-redox equilibria model used for the interpretation of NMR data of D. gigas cytochrome c3 [Santos, H., Moura, J.J.G., Moura, I., LeGall, J. & Xavier, A. V. (1984) Eur. J. Biochem. 141, 283-296] is discussed in terms of the EPR results.

Moura, JW, Stocco dos Santos RC, Dagli ML, D'Angelino JL, Birgel EH, Becak W.  1988.  Chromosome aberrations in cattle raised on bracken fern pasture, Sep 15. Experientia. 44:785-8., Number 9 AbstractWebsite

Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.

Moura, I, Liu MY, Costa C, Liu MC, Pai G, Xavier AV, Legall J, Payne WJ, Moura JJ.  1988.  Spectroscopic characterization of a high-potential monohaem cytochrome from Wolinella succinogenes, a nitrate-respiring organism. Redox and spin equilibria studies, Nov 15. Eur J Biochem. 177:673-82., Number 3 AbstractWebsite

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

Legall, J, Prickril BC, Moura I, Xavier AV, Moura JJ, Huynh BH.  1988.  Isolation and characterization of rubrerythrin, a non-heme iron protein from Desulfovibrio vulgaris that contains rubredoxin centers and a hemerythrin-like binuclear iron cluster, Mar 8. Biochemistry. 27:1636-42., Number 5 AbstractWebsite

A new non-heme iron protein from the periplasmic fraction of Desulfovibrio vulgaris (Hildenbourough NCIB 8303) has been purified to homogeneity, and its amino acid composition, molecular weight, redox potential, iron content, and optical, EPR, and Mossbauer spectroscopic properties have been determined. This new protein is composed of two identical subunits with subunit molecular weight of 21,900 and contains four iron atoms per molecule. The as-purified oxidized protein exhibits an optical spectrum with absorption maxima at 492, 365, and 280 nm, and its EPR spectrum shows resonances at g = 4.3 and 9.4, characteristic of oxidized rubredoxin. The Mossbauer data indicate the presence of approximately equal amounts of two types of iron; we named them the Rd-like and the Hr-like iron due to their similarity to the iron centers of rubredoxins (Rds) and hemerythrins (Hrs), respectively. For the Rd-like iron, the measured fine and hyperfine parameters (D = 1.5 cm-1, E/D = 0.26, delta EQ = -0.55 mm/s, delta = 0.27 mm/s, Axx/gn beta n = -16.5 T, Ayy/gn beta n = -15.6 T, and Azz/gn beta n = -17.0 T) are almost identical with those obtained for the rubredoxin from Clostridium pasteurianum. Redox-titration studies monitored by EPR, however, showed that these Rd-like centers have a midpoint redox potential of +230 +/- 10 mV, approximately 250 mV more positive than those reported for rubredoxins. Another unusual feature of this protein is the presence of the Hr-like iron atoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Day, EP, Peterson J, Bonvoisin JJ, Moura I, Moura JJ.  1988.  Magnetization of the oxidized and reduced three-iron cluster of Desulfovibrio gigas ferredoxin II, Mar 15. J Biol Chem. 263:3684-9., Number 8 AbstractWebsite

The saturation magnetizations of the three iron cluster of ferredoxin II of Desulfovibrio gigas in both the oxidized and reduced states have been studied at fixed magnetic fields up to 4.5 tesla over the temperature range from 1.8 to 200 K. The low field (0.3 tesla) susceptibility of oxidized ferredoxin II obeys the Curie law over this entire temperature range. This establishes -2Jox greater than 200 cm-1 as the lower limit for the antiferromagnetic exchange coupling of oxidized ferredoxin II. The saturation magnetizations of reduced ferredoxin II at several fixed fields yield a nested family of curves which can be fit with spin S = 2 and D = -2.7(4) cm-1 (with E/D assigned the value 0.23 as determined by Mossbauer and EPR spectra). The low field susceptibility of reduced ferredoxin II also obeys the Curie law from approximately 4 up to 200 K. This establishes -2Jred greater than 40 cm-1 as the lower limit for the antiferromagnetic coupling of reduced ferredoxin II.

Patil, DS, Moura JJ, He SH, Teixeira M, Prickril BC, Dervartanian DV, Peck, H. D. J, Legall J, Huynh BH.  1988.  EPR-detectable redox centers of the periplasmic hydrogenase from Desulfovibrio vulgaris, Dec 15. J Biol Chem. 263:18732-8., Number 35 AbstractWebsite

The periplasmic hydrogenase of Desulfovibrio vulgaris (Hildenbourough NCIB 8303) belongs to the category of [Fe] hydrogenase which contains only iron-sulfur clusters as its prosthetic groups. Amino acid analyses were performed on the purified D. vulgaris hydrogenase. The amino acid composition obtained compared very well with the result derived from the nucleotide sequence of the structural gene (Voordouw, G., Brenner, S. (1985) Eur. J. Biochem. 148, 515-520). Detailed EPR reductive titration studies on the D. vulgaris hydrogenase were performed to characterize the metal centers in this hydrogenase. In addition to the three previously observed EPR signals (namely, the "isotropic" 2.02 signal, the rhombic 2.10 signal, and the complex signal of the reduced enzyme), a rhombic signal with resonances at the g-values of 2.06, 1.96, and 1.89 (the rhombic 2.06 signal) was detected when the samples were poised at potentials between 0 and -250 mV (with respect to normal hydrogen electrode). The midpoint redox potentials for each of the four EPR-active species were determined, and the characteristics of each EPR signal are described. Both the rhombic 2.10 and 2.06 signals exhibit spectral properties that are distinct from a ferredoxin-type [4Fe-4S] cluster and are proposed to originate from the same H2-binding center but in two different conformations. The complex signal of the reduced hydrogenase has been shown to represent two spin-spin interacting ferredoxin-type [4Fe-4S]1+ clusters (Grande, H. J., Dunham, W. R., Averill, B., Van Dijk, C., and Sands, R. H. (1983) Eur. J. Biochem. 136, 201-207). The titration data indicated a strong cooperative effect between these two clusters during their reduction. In an effort to accurately estimate the number of iron atoms/molecule of hydrogenase, plasma emission and chemical methods were used to determine the iron contents in the samples; and four different methods, including amino acid analysis, were used for protein determination. The resulting iron stoichiometries were found to be method-dependent and vary over a wide range (+/- 20%). The uncertainties involved in the determination of iron stoichiometry are discussed.

Liu, MC, Costa C, Coutinho IB, Moura JJ, Moura I, Xavier AV, Legall J.  1988.  Cytochrome components of nitrate- and sulfate-respiring Desulfovibrio desulfuricans ATCC 27774, Dec. J Bacteriol. 170:5545-51., Number 12 AbstractWebsite

Three multiheme c-type cytochromes--the tetraheme cytochrome c3 (molecular weight [MW] 13,500), a dodecaheme cytochrome c (MW 40,800), and a "split-Soret" cytochrome c (MW 51,540), which is a dimer with 2 hemes per subunit (MW 26,300)--were isolated from the soluble fraction of Desulfovibrio desulfuricans (ATCC 27774) grown under nitrate- or sulfate-respiring conditions. Two of them, the dodecaheme and the split-Soret cytochromes, showed no similarities to any of the c-type cytochromes isolated from other sulfate-reducing bacteria, while the tetraheme cytochrome c3 appeared to be analogous to the cytochrome c3 found in other sulfate-reducing bacteria. For all three multiheme c-type cytochromes isolated, the homologous proteins from nitrate- and sulfate-grown cells were indistinguishable in amino acid composition, physical properties, and spectroscopic characteristics. It therefore appears that the same c-type cytochrome components are present when D. desulfuricans ATCC 27774 cells are grown under either condition. This is in contrast to the considerable difference found in Pseudomonas perfectomarina (Liu et al., J. Bacteriol. 154:278-286, 1983), a marine denitrifier, when the cells are grown on nitrate or oxygen as the terminal electron acceptor. In addition, two spectroscopy methods capable of revealing minute structural variations in proteins provided identical information about the tetraheme cytochrome c3 from nitrate-grown and sulfate-grown cells.

Saint-Martin, P, Lespinat PA, Fauque G, Berlier Y, Legall J, Moura I, Teixeira M, Xavier AV, Moura JJ.  1988.  Hydrogen production and deuterium-proton exchange reactions catalyzed by Desulfovibrio nickel(II)-substituted rubredoxins, Dec. Proc Natl Acad Sci U S A. 85:9378-80., Number 24 AbstractWebsite

The nickel tetrahedral sulfur-coordinated core formed upon metal replacement of the native iron in Desulfovibrio sp. rubredoxins is shown to mimic the reactivity pattern of nickel-containing hydrogenases with respect to hydrogen production, deuterium-proton exchange, and inhibition by carbon monoxide.

Fauque, G, Peck, H. D. J, Moura JJ, Huynh BH, Berlier Y, Dervartanian DV, Teixeira M, Przybyla AE, Lespinat PA, Moura I,, et al.  1988.  The three classes of hydrogenases from sulfate-reducing bacteria of the genus Desulfovibrio, Dec. FEMS Microbiol Rev. 4:299-344., Number 4 AbstractWebsite

Three types of hydrogenases have been isolated from the sulfate-reducing bacteria of the genus Desulfovibrio. They differ in their subunit and metal compositions, physico-chemical characteristics, amino acid sequences, immunological reactivities, gene structures and their catalytic properties. Broadly, the hydrogenases can be considered as 'iron only' hydrogenases and nickel-containing hydrogenases. The iron-sulfur-containing hydrogenase ([Fe] hydrogenase) contains two ferredoxin-type (4Fe-4S) clusters and an atypical iron-sulfur center believed to be involved in the activation of H2. The [Fe] hydrogenase has the highest specific activity in the evolution and consumption of hydrogen and in the proton-deuterium exchange reaction and this enzyme is the most sensitive to CO and NO2-. It is not present in all species of Desulfovibrio. The nickel-(iron-sulfur)-containing hydrogenases [( NiFe] hydrogenases) possess two (4Fe-4S) centers and one (3Fe-xS) cluster in addition to nickel and have been found in all species of Desulfovibrio so far investigated. The redox active nickel is ligated by at least two cysteinyl thiolate residues and the [NiFe] hydrogenases are particularly resistant to inhibitors such as CO and NO2-. The genes encoding the large and small subunits of a periplasmic and a membrane-bound species of the [NiFe] hydrogenase have been cloned in Escherichia (E.) coli and sequenced. Their derived amino acid sequences exhibit a high degree of homology (70%); however, they show no obvious metal-binding sites or homology with the derived amino acid sequence of the [Fe] hydrogenase. The third class is represented by the nickel-(iron-sulfur)-selenium-containing hydrogenases [( NiFe-Se] hydrogenases) which contain nickel and selenium in equimolecular amounts plus (4Fe-4S) centers and are only found in some species of Desulfovibrio. The genes encoding the large and small subunits of the periplasmic hydrogenase from Desulfovibrio (D.) baculatus (DSM 1743) have been cloned in E. coli and sequenced. The derived amino acid sequence exhibits homology (40%) with the sequence of the [NiFe] hydrogenase and the carboxy-terminus of the gene for the large subunit contains a codon (TGA) for selenocysteine in a position homologous to a codon (TGC) for cysteine in the large subunit of the [NiFe] hydrogenase. EXAFS and EPR studies with the 77Se-enriched D. baculatus hydrogenase indicate that selenium is a ligand to nickel and suggest that the redox active nickel is ligated by at least two cysteinyl thiolate and one selenocysteine selenolate residues.(ABSTRACT TRUNCATED AT 400 WORDS)

Stewart, DE, Legall J, Moura I, Moura JJ, Peck, H. D. J, Xavier AV, Weiner PK, Wampler JE.  1988.  A hypothetical model of the flavodoxin-tetraheme cytochrome c3 complex of sulfate-reducing bacteria, Apr 5. Biochemistry. 27:2444-50., Number 7 AbstractWebsite

A hypothetical model of the flavodoxin-tetraheme cytochrome c3 electron-transfer complex from the sulfate-reducing bacterium Desulfovibrio vulgaris has been constructed by using interactive computer graphics based on electrostatic potential field calculations and previous NMR experiments. Features of the proposed complex are (1) van der Waals contact between the flavin mononucleotide prosthetic group of flavodoxin and one heme of the cytochrome, (2) unique complementarity of electrostatic fields between the region surrounding this heme and the region surrounding the exposed portion of the flavin mononucleotide group of flavodoxin, and (3) no steric interferences between the two polypeptide chains in the complex. This complex is consistent with all structural and spectroscopic data available.

Kowal, AT, Zambrano IC, Moura I, Moura JJG, Legall J, Johnson MK.  1988.  Electronic and magnetic properties of nickel-substituted rubredoxin: a variable-temperature magnetic circular dichroism study, 1988/04/01. Inorganic Chemistry. 27:1162-1166., Number 7: American Chemical Society AbstractWebsite
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Moura, I, Legall J, Lino AR, Peck HD, Fauque G, Xavier AV, Dervartanian DV, Moura JJG, Huynh BH.  1988.  Characterization of two dissimilatory sulfite reductases (desulforubidin and desulfoviridin) from the sulfate-reducing bacteria. Moessbauer and EPR studies, 1988/02/17. Journal of the American Chemical Society. 110:1075-1082., Number 4: American Chemical Society AbstractWebsite
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Huynh, BH, Moura I, Lino AR, Moura JJG, Legall J.  1988.  Characterization of two dissimilatory sulfite reductases from sulfate-reducing bacteria, 1988. Hyperfine Interactions. 42:905-908., Number 1-4 AbstractWebsite
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Moura, JJG, Moura I, Teixeira M, Xavier AV, Fauque GD, Legall J.  1988.  NICKEL-CONTAINING HYDROGENASES, 1988. Metal Ions in Biological Systems. 23:285-314. AbstractWebsite
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Ramos, MJJ, Dionísio M, Gonçalves R, Diogo H.  1988.  A further view on the calculation of the enthalpy of cavity formation in liquids. The influence of the cavity size and shape. Canadian Journal of Chemistry. 66(11):2894-2902.Website
Huynh, B, Moura I, Lino A, Moura J, Legall J.  1988.  Characterization of two dissimilatory sulfite reductases from sulfate-reducing bacteria. Hyperfine Interactions. 42:905-908., Number 1: Springer Netherlands AbstractWebsite

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

Kremer, DR, Veenhuis M, Fauque G, Peck HD, Legall J, Lampreia J, Moura JJG, Hansen TA.  1988.  Immunocytochemical localization of APS reductase and bisulfite reductase in three <i>Desulfovibrio</i> species. Archives of Microbiology. 150:296-301., Number 3: Springer Berlin / Heidelberg AbstractWebsite

The localization of APS reductase and bisulfite reductase in Desulfovibrio gigas, D. vulgaris Hildenborough and D. thermophilus was studied by immunoelectron microscopy. Polyclonal antibodies were raised against the purified enzymes from each strain. Cells fixed with formaldehyde/glutaraldehyde were embedded and ultrathin sections were incubated with antibodies and subsequently labeled with protein A-gold. The bisulfite reductase in all three strains and APS reductase in d. gigas and D. vulgaris were found in the cytoplasm. The labeling of d. thermophilus with APS reductase antibodies resulted in a distribution of gold particles over the cytoplasmic membrane region. The localization of the two enzymes is discussed with respect to the mechanism and energetics of dissimilatory sulfate reduction.

Teixeira, G, Aviles T, Dias AR, Pina F.  1988.  A KINETIC-STUDY OF PHOTOSUBSTITUTION OF CARBON-MONOXIDE AND TRIPHENYLPHOSPHINE IN COMPLEXES MN(ETA-5-CH3C5H4)(CO)3-N(PPH3)N (N=0, 1 AND 2). Journal of Organometallic Chemistry. 353:83-91., Number 1 AbstractWebsite
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FIGUEIREDO, P, Pina F.  1988.  A PHOTOCATALYTIC CYCLE FOR MILD OXIDATION BY DIOXYGEN OF SUBSTRATES EASILY OXIDIZABLE BY IODINE. Journal of Photochemistry and Photobiology a-Chemistry. 44:57-61., Number 1 AbstractWebsite
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Pina, F, Maestri M.  1988.  PHOTOCHEMISTRY OF CO(EDTA)–I-SYSTEM IN AQUEOUS-SOLUTIONS. Inorganica Chimica Acta. 142:223-228., Number 2 AbstractWebsite
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