Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.12.7.2 (hydrogenase)
 3,522 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutants deficient in the metabolism of one-carbon compounds have been obtained by treating Paracoccus denitrificans with the mutagen N-methyl-N'-nitro-N-nitrosoguanidine. Mutants were selected without enrichment procedures by newly developed plate screening tests. The obtained mutants were characterized by their growth responses, cytochrome composition, enzyme activities, and immunogenic reaction with antisera against methanol dehydrogenase. By these criteria five mutant classes could be distinguished. Class I mutants are involved in the expression of methanol dehydrogenase. Three mutants of this class have a defect in the structural gene. A double mutant was found with defects in the expression of both methanol dehydrogenase and hydrogenase. Class II mutants have a defect in a regulatory gene involved in the regulation of both methanol dehydrogenase and methylamine dehydrogenase. Class III mutants are deficient in formaldehyde metabolism. A defect may exist in the expression of a second non-NAD-linked formaldehyde dehydrogenase which was postulated to be involved in C1 metabolism. Class IV mutants are deficient in cytochrome c. Mutants of class V have a defect in synthesis of the molybdenum cofactor essential for the function of formate dehydrogenase.
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PMID:Isolation and characterization of Paracoccus denitrificans mutants with defects in the metabolism of one-carbon compounds. 390 63

Several dissimilatory, sulfate-reducing bacteria were isolated from the rumen fluid of sheep fed purified diets containing sulfate. One isolate, strain D, was selected for characterization. This organism is a nonsporeforming, obligately anaerobic, mesophilic, nonmotile, gram-negative, straight rod. Cell-free extracts show absorption maxima for cytochrome c(3) and desulfoviridin, characteristic of Desulfovibrio. Carbohydrates, as a sole carbon source, will support growth. Lactate supports growth in the presence of sulfate, not in its absence, whereas glucose or pyruvate support growth either in the presence or absence of sulfate. The isolate has a deoxyribonucleic acid base composition of 61.2% guanine plus cytosine, which is similar to that of several other species of Desulfovibrio; however, it differs from previously described species in morphology, motility, and carbon source utilization. Cell-free extracts of this bacterium exhibit adenosine 5'-triphosphate-sulfurylase, adenosine-5'-phosphosulfate-reductase, and hydrogenase activity. After incubation of cell-free extracts with adenine 5'-triphosphate and (35)SO(4) (2-), adenosine-5'-phosphosulfate rather than 3'-phosphoadenosine-5'-phosphosulfate was shown to be labeled, indicating that the pathway of sulfate reduction in this organism is similar to that of other dissimilatory sulfate reducers. This is the first report of a Desulfovibrio sp. isolated from the rumen.
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PMID:Sulfate reduction by a Desulfovibrio species isolated from sheep rumen. 447 25

The soluble hydrogenase of Desulfovibrio vulgaris was purified and some of its properties are described. The molecular weight was determined for the enzyme by sedimentation equilibrium (45,400) and amino acid analysis (44,800). The hydrogenase appears to be a loosely coiled molecule or to have a high axial ratio, which is reflected in an unusually low sedimentation coefficient (2.58S) and a low diffusion coefficient (D 5.85). The molecular weight of the hydrogenase (41,000), as calculated by the Svedberg equation, was in general agreement with the sedimentation equilibrium molecular weight. Amino acid analysis revealed the presence of six halfcystine residues per mole of enzyme and a total of 417 amino acid residues. The specificity of the hydrogenase and its capacity to reduce certain low potential dyes and cytochrome c(3) was studied. Metal analysis of the hydrogenase indicated the presence of 1 mole of ferrous iron per mole of enzyme.
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PMID:Purification and properties of a hydrogenase from Desulfovibrio vulgaris. 554 Oct 10

Crude extracts of Desulfovibrio vulgaris reduced sulfite to sulfide. Ammonium sulfate fractionation of crude extracts separated a thiosulfate-forming system from sulfite- and thiosulfate-reductase activities. Further purification by sucrose density centrifugation separated the thiosulfate-forming system into two components, both of which were required for the reaction. In addition to these two components, cytochrome c(3), ferredoxin, and hydrogenase were required to form thiosulfate from sulfite. By absorption spectra and from the effect of pH and substrate concentration, the ionic species acting as the substrate for thiosulfate-formation was concluded to be bisulfite.
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PMID:Formation of thiosulfate from sulfite by Desulfovibrio vulgaris. 580 6

Maximum growth of Campylobacter fetus subsp. jejuni, strain C-61, occurred when the cultures were incubated with shaking in atmospheres containing approximately 30% hydrogen, 5% oxygen, and 10% CO2. Suspensions of cells grown under these conditions consumed oxygen with formate as the substrate in the presence of 0.33 mM cyanide, which completely inhibited respiration with ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine and with lactate. Spectroscopic evidence with intact cells suggested that a form of cytochrome c, reducible with formate but not with lactate or ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine, can be reoxidized by a cyanide-insensitive system. Analysis of membranes from the cells showed high- and low-potential forms of cytochrome c, cytochrome b, and various enzymes, including hydrogenase, formate dehydrogenase, and fumarate reductase. The predominant carbon monoxide-binding pigment appeared to be a form of cytochrome c, but the spectra also showed evidence of cytochrome o. The membrane cytochromes were reduced by hydrogen in the presence of 2-heptyl-4-hydroxyquinoline-N-oxide at concentrations which prevented the reduction of cytochrome c with succinate as the electron donor. Reoxidation of the substrate-reduced cytochromes by oxygen was apparently mediated by cyanide-sensitive and cyanide-insensitive systems. The membranes also had hydrogen-fumarate oxidoreductase activity mediated by cytochrome b. We conclude that C. fetus jejuni has high- and low-potential forms of cytochrome which are associated with a complex terminal oxidase system.
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PMID:Aerobic and anaerobic respiratory systems in Campylobacter fetus subsp. jejuni grown in atmospheres containing hydrogen. 628 61

The nitrogen-fixing, aerobic hydrogen-oxidizing bacterium Alcaligenes latus forms hydrogenase when growing lithoautotrophically with hydrogen as electron donor and carbon dioxide as sole carbon source or when growing heterotrophically with N2 as sole nitrogen source. The hydrogenase is membrane-bound and relatively oxygen-sensitive. The enzymes formed under both conditions are identical on the basis of the following criteria: molecular mass, mobility in polyacrylamide gel electrophoresis, Km value for hydrogen (methylene blue reduction), stability properties, localization, and cross-reactivity to antibodies raised against the 'autotrophic' hydrogenase. The hydrogenase was solubilized by Triton X-100 and deoxycholate treatment and purified by ammonium sulfate precipitation and chromatography on Phenyl-Sepharose C1-4B, DEAE-Sephacel and Matrix Gel Red A under hydrogen to homogeneity to a specific activity of 113 mumol H2 oxidized/min per mg protein (methylene blue reduction). SDS gel electrophoresis revealed two nonidentical subunits of molecular weights of 67 000 and 34 000, corresponding to a total molecular weight of 101 000. The pure enzyme was able to reduce FAD, FMN, riboflavin, flavodoxin isolated from Megasphaera elsdenii, menadione and horse heart cytochrome c as well as various artificial electron acceptors. The reversibility of the hydrogenase function was demonstrated by H2 evolution from reduced methyl viologen.
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PMID:Purification and properties of the membrane-bound hydrogenase from N2-fixing Alcaligenes latus. 630 22

A low molecular weight iron-sulfur protein has been purified from Tritrichomonas foetus by deoxycholate extraction of whole cells, ion exchange chromatography, and gel filtration. The purified protein was essentially homogeneous as judged by isoelectric focusing, polyacrylamide gel electrophoresis, and gel filtration. A pI of 4.3 was observed. The molecular weight of the protein was estimated to be 12,000. Chemical and spectral analysis showed the protein to have a [2Fe-2S] cluster. The absorbance spectrum of the oxidized protein showed maxima at 280, 340, 458 and shoulders at 410 and 550 nm. The maximum observed A458/A280 ratio was 0.82 and the absorbance of the oxidized protein at 458 nm was 8,000 M-1 X cm-1. The low temperature EPR spectrum of the protein reduced with dithionite revealed axial symmetry with features at g values of g = 1.94 and g = 2.02. The oxidized protein gave no EPR signal in the g = 1.8 to 2.2 range. Cell fractionation studies indicated the localization of this protein in the hydrogenosome. The protein was able to function as an electron transport component in the reduction of metronidazole (a 5-nitroimidazole derivative) by pyruvate:ferredoxin oxidoreductase and hydrogenase from T. foetus and also from Trichomonas vaginalis and Clostridium pasteurianum as well as in the reduction of cytochrome c by plant NADPH:ferredoxin oxidoreductase. This protein has the characteristics of a ferredoxin and is likely to be a physiological electron carrier in hydrogenosomal pyruvate oxidation.
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PMID:Hydrogenosomal ferredoxin of the anaerobic protozoon, Tritrichomonas foetus. 631 59

A spectroelectrochemical study is described of the sixteen hemes in the high-molecular-mass, monomeric cytochrome c (Hmc) from the periplasmic space of Desulfovibrio vulgaris, strain Hildenborough. One of the hemes has special properties. In the oxidized state at pH 7 it is predominantly high-spin, S = 5/2, with a g perpendicular value of less than 6 indicative of quantum-mechanical mixing with a low-lying (800 cm-1) S = 3/2 state; the balance is probably a low-spin derivative. The high-spin heme has an Em.7.5 value of +61 mV. The fifteen other hemes are low-spin bis-histidine coordinated with Em.7.5 values of approximately -0.20 V. Two of these hemes exhibit very anisotropic EPR spectra with a g1 value of 3.65 characteristic for strained bis-histidine coordination. A previous proposal, namely that methionine is coordinated to one of the hemes [Pollock, W.B.R., Loufti, M. Bruschi, M. Rapp-Giles, B.J., Wall, J. & Voordouw, G. (1991) J. Bacteriol. 173, 220] is disproved using spectroscopic evidence. Contrasting electrochemical data sets from two previous studies [Tan, J. & Cowan, J.A. (1990) Biochemistry 29, 4886; Bruschi, M., Bertrand, P., More, C., Leroy, G., Bonicel, J., Haladjian, J., Chottard, G., Pollock, W.B.R. & Voordouw, G. (1992) Biochemistry 31, 3281] are not consistent with our EPR titration results and are not reproducible. Hmc can be reduced by D. vulgaris Fe-hydrogenase in the presence of molecular hydrogen.
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PMID:Axial coordination and reduction potentials of the sixteen hemes in high-molecular-mass cytochrome c from Desulfovibrio vulgaris (Hildenborough). 792 51

A high molecular weight c-type cytochrome (Hmc) was purified and characterized from Desulfovibrio gigas. The molecular weight was estimated to be 67 kDa by SDS-PAGE and its N-terminus is homologous to those of the 16 hemes containing high molecular weight cytochrome c from Desulfovibrio vulgaris strains Hildenborough and Miyazaki. The purified hemoprotein shows c-type cytochrome absorption spectrum with e533 (red) = 368 mM-1.cm-1. A band at 640 nm, characteristic of high-spin hemes, was detected. The EPR spectra show the presence of two high-spin heme species, plus several non-equivalent low-spin hemes. The heme reduction potentials, at pH 7.6, range from -50 mV to -315 mV. In contrast to what has been described for D. vulgaris Hmc, the protein isolated from D. gigas directly accepts electrons from hydrogenase and further reduces other redox proteins.
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PMID:Isolation and characterization of a high molecular weight cytochrome from the sulfate reducing bacterium Desulfovibrio gigas. 803 21

A new FMN-containing flavoprotein isolated from Desulfovibrio gigas provided maximum coupling efficiency for the reduction of bisulfite from molecular H2. This protein, which is distinct from flavodoxin and for which the name flavoredoxin is proposed, is required for reconstitution of an electron transfer chain between hydrogenase and bisulfite reductase. A Ca(2+)-binding protein functions as a modulator in the presence of Ca2+ in the process. The finding of a membrane-bound cytochrome c with a molecular weight of 104,000 Da that is also active in this electron transfer chain provides an explanation for the energetic linkage between periplasmic and cytoplasmic proteins in this sulfate-reducing bacterium.
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PMID:Isolation and characterization of flavoredoxin, a new flavoprotein that permits in vitro reconstitution of an electron transfer chain from molecular hydrogen to sulfite reduction in the bacterium Desulfovibrio gigas. 838 52


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