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At least 19 recordsLinked to original sources
PubMed1979

Study of cytochromes c3 from Desulfovibrio vulgaris (Hildenborough) and Desulfovibrio desulfuricans (Norway) by differential pulse polarography and spectroelectrochemical method.

(1) Cytochromes c3 from Desulfovibrio vulgaris (Hildenborough strain) and Desulfovibrio desulfuricans (Norway strain) have been studied by differential pulse polarography and spectroelectrochemical method. Both cytochromes exhibit two reduction potential values Eh approximately --0.25 and --0.34 V (D. vulgaris), Eh approximately --0.16 and --0.34 V (D. desulfuricans). (2) Titrations by dithionite and controlled potential electrolysis coupled with polarography and spectrophotometry suggest that in both cases electronic exchanges are rapid.

Cytochromes↗
PubMed1977

Growth of desulfovibrio in lactate or ethanol media low in sulfate in association with H2-utilizing methanogenic bacteria.

In the analysis of an ethanol-CO(2) enrichment of bacteria from an anaerobic sewage digestor, a strain tentatively identified as Desulfovibrio vulgaris and an H(2)-utilizing methanogen resembling Methanobacterium formicicum were isolated, and they were shown to represent a synergistic association of two bacterial species similar to that previously found between S organism and Methanobacterium strain MOH isolated from Methanobacillus omelianskii. In lowsulfate media, the desulfovibrio produced acetate and H(2) from ethanol and acetate, H(2), and, presumably, CO(2) from lactate; but growth was slight and little of the energy source was catabolized unless the organism was combined with an H(2)-utilizing methanogenic bacterium. The type strains of D. vulgaris and Desulfovibrio desulfuricans carried out the same type of synergistic growth with methanogens. In mixtures of desulfovibrio and strain MOH growing on ethanol, lactate, or pyruvate, diminution of methane produced was stoichiometric with the moles of sulfate added, and the desulfovibrios grew better with sulfate addition. The energetics of the synergistic associations and of the competition between the methanogenic system and sulfate-reducing system as sinks for electrons generated in the oxidation of organic materials such as ethanol, lactate, and acetate are discussed. It is suggested that lack of availability of H(2) for growth of methanogens is a major factor in suppression of methanogenesis by sulfate in natural ecosystems. The results with these known mixtures of bacteria suggest that hydrogenase-forming, sulfate-reducing bacteria could be active in some methanogenic ecosystems that are low in sulfate.

Acetates↗
PubMed1977

Purification and characterization of cytochrome c3, ferredoxin, and rubredoxin isolated from Desulfovibrio desulfuricans Norway.

Different electron carriers of the non-desulfoviridin-containing, sulfate-reducing bacterium Desulfovibrio desulfuricans (Norway strain) have been studied. Two nonheme iron proteins, ferredoxin and rubredoxin, have been purified. This ferredoxin contains four atoms of non-heme iron and acid-labile sulfur and six residues of cysteine per molecule. Its amino acid composition suggests that it is homologous with the other Desulfovibrio ferredoxins. The rubredoxin is also an acidic protein of 6,000 molecular weight and contains one atom of iron and four cysteine residues per molecule. The amino acid composition and molecular weight of the cytochrome c3 from D. desulfuricans (strain Norway 4) are reported. Its spectral properties are very similar to those of the other cytochromes c3 (molecular weight, 13,000) of Desulfovibrio and show that it contains four hemes per molecule. This cytochrome has a very low redox potential and acts as a carrier in the coupling of hydrogenase and thiosulfate reductase in extracts of Desulfovibrio gigas and Desulfovibrio desulfuricans (Norway strain) in contrast to D. gigas cytochrome c3 (molecular weight, 13,000). A comparison of the activities of the cytochrome c3 (molecular weight, 13,000) of D. gigas and that of D. desulfuricans in this reaction suggests that these homologous proteins can have different specificity in the electron transfer chain of these bacteria.

Amino Acids↗
PubMed1979

Isolation and characterization of a rubredoxin and two ferredoxins from Desulfovibrio africanus.

Rubredoxin and two distinct ferredoxins have been purified from Desulfovibrio africanus. The rubredoxin has a molecular weight of 6000 while the ferredoxins appear to be dimers of identical subunits of approximately 6000 to 7000 molecular weight. Rubredoxin contains one iron atom, no acid-labile sulfide and four cysteine residues per molecule. Its absorbance ratio A278/A490 is 2.23 and its amino acid composition is characterized by the absence of leucine and a preponderance of acidic amino acids. The two ferredoxins, designated I and II, are readily separated on DEAE-cellulose. The amino acid compositions of ferredoxins I and II show them to be different protein species; the greater number of acidic amino acid residues in ferredoxin I than in ferredoxin II appears to account for separation based on electronic charge. Both ferredoxins contain four iron atoms, four acid-labile residues per molecule. Spectra of the two ferredoxins differ from those of ferredoxins of other Desulfovibrio species by exhibiting a pronounced absorption peak at 283 nm consistent with an unusual high content of aromatic residues. The A385/A283 absorbance ratio of ferredoxins I and II are 0.56 and 0.62, respectively. The N-terminal sequencing data of the two ferredoxins clearly indicate that ferredoxins I and II are different protein species. However, the two proteins exhibit a high degree of homology.

Amino Acid Sequence↗
PubMed1976

Non-heme iron proteins. The amino acid sequence of rubredoxin from Desulfovibrio vulgaris.

A non-heme iron protein, rubredoxin has been isolated from the sulfate-reducing bacterium, Desulfovibrio vulgaris, strain Hildenborough. The complete amino acid sequence has been established. The 52 amino acid residues of the protein were aligned with the aid of tryptic and chymotryptic peptides and of a fragment produced by cleavage of the Asn-Gly bond (22-23) by hydroxylamine. The sequence of the first 30 residues of the molecule was determined using an automatic sequenator, after removal of the N-terminal methionine by CNBr. In comparing this sequence with those of Micrococcus aerogenes, Clostridium pasteurianum and Peptostreptococcus elsdenii rubredoxins, a high degree of mutation was observed between these homologous proteins. It has been shown that 20 amino acid residues occurred in identical positions. The locations of the four cysteine residues were found to be invariable. A crystallographic study of the Desulfovibrio vulgaris rubredoxin is in progress.

Amino Acid Sequence↗
PubMed1979

Cytochrome c3 from the sulfate-reducing anaerobe Desulfovibrio africanus Benghazi: purification and properties.

Cytochrome c3 was purified from Desulfovibrio africanus Benghazi by extraction with alkaline deoxyribonuclease, fractionation with ammonium sulfate, batch elution from carboxymethyl Sephadex followed by chromatography on the same resin, and gel filtration on Sephadex G-75. The preparation was judge homogeneous by a variety of criteria. The molecular weight was determined in an analytical ultracentrifuge, and values between 14,400 and 15,490 were obtained, depending upon the presumed value of partial specific volume. Gel filtration on a calibrated column of Sephadex G-75 gave a value of 14,900 daltons. The amino acid composition was very similar to that observed for the cytochrome from other species of Desulfovibrio, with the exception of increased levels of ThR and PhE. S-Carboxymethylation of the protein before and after heme removal by HgCl2 demonstrated eight Cys molecules involved in heme binding or four heme sites per molecule. Titration with sodium dithionite under N2 gave an electrochemical potential (E' 0) of -276 mV relative to the normal hydrogen electrode. Electrochemical titration of the cytochrome gave a Nernst plot with two linear regions with E' 0 values of -0.376 and -0.534 V. The spectra produced at various potentials exhibited shifts in isosbestic points upon reduction, suggesting changes in conformation during the reaction.

Amino Acids↗
PubMed1976

Bouyant density, conversion formulae, and the mole percent guanosine + cytosine content of Desulfovibrio sp.

A reevaluation of the original buoyant density conversion formula used to calculate the molar percentage guanosine + cytosine (% G + C) contents of the accepted species of genus Desulfovibrio has been undertaken. It would appear that the formula used gives values 4-5% lower than those obtained using formulae more generally cited in modern literature. Recalculations of % G + C content values for Lesulfovibrio DNA are presented using the formulae of three different workers, and are compared with those values originally used in the classification of genus Desulfovibrio.

Centrifugation, Density Gradient↗
PubMed1977

The tricarboxylic and acid pathway in Desulfovibrio.

Strains of two species of Desulfovibrio were examined for enzymes of the tricarboxylic acid cycle and related pathways. Pyruvate carboxylase (EC6.4.1.1) is present, and alpha-ketoglutarate is formed via the tricarboxylic acids. Glutamate, but not succinyl-CoA, arises from alpha-ketoglutarate. A pathway exists from pyruvate by malic enzyme (EC 1.1.1.39) activity to malate, then fumarate and succinate, again with no evidence of succinyl-CoA formation. The enzymes concerned with metabolism of these dicarboxylic acids show greater activity in the strains that can grow by fumarate dismutation. Glutamate (or glutamine), alpha-ketoglutarate, and yeast extract repress the enzymes that metabolize the tricarboxylic acids. There appears to be no glyoxylate cycle in Desulfovibrio vulgaris or D. desulfuricans.

Anaerobiosis↗
PubMed1979

Oxidative phosphorylation linked to the dissimilatory reduction of elemental sulphur by Desulfovibrio.

Hydrogenase and cytochrome c3 purified from Desulfovibrio gigas and D. desulfuricans strain Norway form a soluble complex which is capable of transferring electrons from molecular hydrogen to colloidal sulphur (S0). In this reaction, sulphur is reduced to hydrogen sulphide. Since both strains are capable of growth using elemental sulphur as terminal electron acceptor, it was of interest to check for oxidative phosphorylation in this sulphur reduction sytem. Membranes isolated from D. gigas or D. desulfuricans strain Norway contain hydrogenase and c-type cytochromes and catalyse the H2 leads to S0 reaction. With D. gigas, esterification of orthophosphate is coupled to the membrane-mediated transfer of electrons from H2 to S0. A P/2e ratio of 0.1 was observed and this value could be reduced by the addition of colloidal sulphur with c2 may be more than a purely chemical reaction. Since whole cells can use sulphur flower while cell-free extracts react only with colloidal sulphur, it is evident that cells handle sulphur in a way which is not yet fully understood.

Adenosine Triphosphate↗
PubMed1975

Purification and properties of thiosulfate reductase from Desulfovibrio gigas.

Thiosulfate reductase of the dissimilatory sulfate-reducing bacterium Desulfovibrio gigas has been purified 415-fold and its properties investigated. The enzyme was unstable during the different steps of purification as well as during storage at - 15 degrees C. The molecular weight of thiosulfate reductase estimated from the chromatographic behaviour of the enzyme on Sephadex G-200 was close to 220000. The absorption spectrum of the purified enzyme exhibited a protein peak at 278 nm without characteristic features in the visible region. Thiosulfate reductase catalyzed the stoichiometric production of hydrogen sulfide and sulfite from thiosulfate, and exhibited tetrathionate reductase activity. It did not show sulfite reductase activity. The optimum pH of thiosulfate reduction occurred between pH 7.4 and 8.0 and its Km value for thiosulfate was calculated to be 5 - 10(-4)M. The sensitivity of thiosulfate reductase to sulfhydryl reagent and the reversal of the inhibition by cysteine indicated that one or more sulfhydryl groups were involved in the catalytic activity. The study of electron transport between hydrogenase and thiosulfate reductase showed that the most efficient coupling was obtained with a system containing cytochromes c3 (Mr = 13000) and c3 (Mr = 26000).

Cold Temperature↗
PubMed1975

Physicochemical properties of flavodoxin from Desulfovibrio vulgaris.

Reductive titration curves of flavodoxin from Desulfovibrio vulgaris displayed two one-electron steps. The redox potential E-2 for the couple oxidized flavodoxin/flavodoxin semiquinone was determined by direct titration with dithionite. E-2 was -149 plus or minus 3 mV (pH 7.78, 25 degrees C). The redox potential E-1 for the couple flavodoxin semiquinone/fully reduced flavodoxin was deduced from the equilibrium concentration of these species in the presence of hydrogenase and H-2. E-1 was -438 plus or minus 8 mV (pH 7.78, 25 degrees C). Light-absorption and fluorescence spectra of flavodoxin in its three redox states have been recorded. Both the rate and extent of reduction of flavodoxin semiguinone with dithionite were found to depend on pH. An equilibrium between the semiquinone and hydroquinone forms occurred at pH values close to the neutrality, even in the presence of a large excess of dithionite, suggesting an ionization in fully reduced flavodoxin with a pK-a = 6.6. The association constants K for the three FMN redox forms with the apoprotein were deduced from the value of K (K = 8 times 10-7 M-1) measured with oxidized EMN at pH 7.0. Oxidized flavodoxin was found to comproportionate with the fully reduced protein (k-comp = 4.3 times 10-3 M-1 times s-1, pH 9.0, 22 degrees C) and with reduced free FMN (K-comp = 44 M-1 times s-1, pH 8.1, 20 degrees C). Fast oxidation of reduced flavodoxin occurred in the presence of O-2. Slower oxidation of semiquinone was dependent on pH in a drastic way.

Desulfovibrio↗
PubMed1979

Purification and properties of cytochrome c-553, an electron acceptor for formate dehydrogenase of Desulfovibrio vulgaris, Miyazaki.

Cytochrome c-553 of Desulfovibrio vulgaris, Miyazaki, was purified to homogeneity. The absorption spectrum of the ferro form has four peaks at 553, 525, 417 and 317 nm with a plateau near 280 nm, and that of the ferri form has three peaks at 525, 410 and 360 nm with a plateau near 280 nm and a shoulder at 560 nm. The millimolar absorbance coefficient of the alpha-peak of the ferro form is 23.9. The molecular weight of cytochrome c-553 is 8000, and it contains one heme. Its isoelectric point is rather alkaline, and its standard redox potential is -0.26 V at pH 7.0. Its amino acid composition is unique; it lacks proline, isoleucine and tryptophan. Ferrocytochrome c-553 does not combine with CO, nor does it transfer electrons directly to various redox carriers such as flavin nucleotides, methylene blue, indigodisulfonate, 5-methylphenazinium methyl sulfate, 1-methoxy-5-methylphenazinium methyl sulfate, viologens and cytochrome c3, but is oxidized by ferricyanide or by O2. Cytochrome c-553 can be reduced by formate dehydrogenase of this bacterium in the presence of formate, but not by hydrogenase under H2. The formate dehydrogenase does not reduce cytochrome c3 in the presence of formate. The systematic name for formate dehydrogenase of D. vulgaris is, therefore, established as formate:ferricytochrome c-553 oxidoreductase in EC subclass 1.22.-.

Aldehyde Oxidoreductases↗
PubMed1975

Effect of enzymic assay conditions on sulfite reduction catalysed by desulfoviridin from Desulfovibrio gigas.

The type and the amount of end products resulting from sulfite reduction catalysed by a single partially purified desulfoviridin preparation from Desulfovibrio gigas were shown to depend upon the enzymic assay conditions employed. Both manometric and spectrophotometric assays were used, with reduced methyl viologen serving as the electron donor in each system. Trithionate, thiosulfate, tetrathionate and sulfide were identified as possible end products. In the manometric assays, sulfide production was favoured by high reduced methyl viologen concentrations, low sulfite concentrations and a pH value of 7.0 as opposed to 6.0. In the spectrophotometric assays, results approaching the stoichiometric conversion of sulfite to sulfide were obtained only at high initial reduced methyl viologen concentrations.

Desulfovibrio↗
PubMed1977

An iron-containing superoxide dismutase from the strict anaerobe Desulfovibrio desulfuricans (Norway 4).

Superoxide dismutase, the enzyme which catalyzes the dismutation of superoxide free radicals (formula: see text) has been purified to homogeneity from the strict anaerobe sulfate-reducing bacterium Desulfovibrio desulfuricans (Norway 4). Its molecular weight is 43,000 and it is composed of two subunits of equal size which are not covalently bound. The enzyme was found to contain iron by atomic absorption and the absence of acid-labile sulfur indicates that it is not an iron-sulfur protein. Electron paramagnetic resonance spectrum revealed that iron occurs in a high spin ferric form. The ultraviolet and visible absorption spectra of the enzyme are presented, as are the results of amino-acid analysis. The data reported allow to conclude that this superoxide dismutase isolated from a strict anaerobe exhibits similar physico-chemical properties as compared to the iron-containing dismutases found in aerobic microorganisms. The significance of the presence of a superoxide dismutase in this strict anaerobe sulfate reducer is discussed.

Amino Acids↗
PubMed1978

Oxidation-reduction studies of the Mo-(2Fe-2S) protein from Desulfovibrio gigas.

Potentiometric titration followed by e.p.r. measurements were used to determine the midpoint reduction potentials of the redox centres of a molybdenum-containing iron-sulphur protein previously isolated from Desulfovibrio gigas, a sulphate-reducing bacterium (Moura, Xavier, Bruschi, Le Gall, Hall & Cammack (1976) Biochem. Biophys. Res. Commun. 728 782-789; Moura, Xavier, Bruschi, Le Gall & Cabral (1977) J. Less Common Metals 54, 555-562). The iron-sulphur centres could readily be distinguished into three types by means of g values, temperature effect, oxidation-reduction potential values and reduction rates. The type-I Fe-S centres are observed at 77 K. They show mid-point potential values of -260mV (Fe-S type IA) and -440 mV (Fe-S type IB). Centres of types IA and IB appear to have similar spectra at 77 K and 24 K. The Fe-S type-II centres are only observed below 65 K and have a midpoint potential of -28mV. Long equilibration times (30 min) with dye mediators under reducing conditions were necessary to observe the very slow equilibrating molybdenum signals. The potential values associated with this signal were estimated to be approx. -415 mV for Mo(VI)/Mo(V) and-530mV for Mo(V)/Mo(IV).

Desulfovibrio↗
PubMed1976

Properties of purified hydrogenase from the particulate fraction of Desulfovibrio vulgaris, Miyazaki.

The properties of purified hydrogenase [EC 1.12.2.1] solubilized from particulate fraction of sonicated Desulfovibrio vulgaris cells are described. The enzyme was a brownish iron-sulfur protein of molecular weight 89,000, composed of two different subunits (mol. wt.: 28,000 and 59,000), and it contained 7-9 iron atoms and 7-8 labile sulfide ions. Molybdenum was not detected in the preparation. The absorption spectrum of the enzyme was characteristic of iron-sulfur proteins. The millimolar absorbance coefficients of the enzyme were about 164 at 280nm, and 47 at 400nm. The absorption spectrum of the enzyme in the visible region changed upon incubating the enzyme under H2 in the presence of cytochrome c3, but not in its absence. This spectral change was due to the reduction of the enzyme. The absorbance ratio at 400nm of the reduced and the oxidized forms of the enzyme was 0.66. The activity of the enzyme was hardly affected by metal-complexing agents such as cyanide, azide, 1,10-phenanthroline, etc., except for CO, which was a strong inhibitor of the enzyme. The activity was inhibited by SH-reagents such as p-chloromercuribenzenesulfonate. The enzyme was significantly resistant to urea, but susceptible to sodium dodecyl sulfate. These properties were very similar to those of clostridial hydrogenase [EC 1.12.7.1], in spite of differences in the acceptor specificity and subunit structure.

Amino Acids↗
PubMed1975

Localized intracellular polyphosphate formation by Desulfovibrio gigas.

The dissimilatory sulphate-reducing bacterium Desulfovibrio gigas, frequently sub-cultured, often contained spherical granules which stained metachromatically with some basic dyes. The granules were examined in situ by transmission electron microscopy of whole organisms and thin sections. The granules were isolated from broken bacteria as a water-insoluble, non-crystalline, white material containing magnesium, phosphorus and organic carbon, but devoid of sulphur and nitrogen. The molar ratio of phosphorus to magnesium (1 to 17) was close to the proportions in magnesium tripolyphosphate. Infrared absorption spectra for the white material and magnesium tripolyphosphate were similar.

Carbon↗