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)

Various sulphate-reducing bacteria differing in the number of genes encoding hydrogenase were shown to ferment lactate in coculture with Methanospirillum hungatei, in the absence of sulphate. The efficiency of interspecies H2 transfer carried out by these species of sulphate-reducing bacteria does not appear to correlate with the distribution of genes coding for hydrogenase. Desulfovibrio vulgaris Groningen, which possesses only the gene for [NiFe] hydrogenase, oxidizes hydrogen in the presence of sulphate and produces some hydrogen during fermentation of pyruvate without electron acceptor. The hydrogenase of D. vulgaris was purified and characterized. It exhibits a molecular mass of 87 kDa and is composed of two different subunits (60 and 28 kDa). D. vulgaris hydrogenase contains 10.6 iron atoms, 0.9 nickel atom and 12 acid-labile sulphur atoms/molecule, and the absorption spectrum of the enzyme is characteristic of an iron-sulphur protein. Maximal H2 uptake and H2 evolution activities were 332 and 230 units/mg protein, respectively. D. vulgaris cells contain exclusively the [NiFe] hydrogenase, whatever the growth conditions, as shown by biochemical and immunological studies. Immunocytolocalization in ultrathin frozen sections of cells grown on lactate and sulphate, on H2 and sulphate and on pyruvate showed that the [NiFe] hydrogenase was located in the periplasmic space. Labelling was enhanced in cells grown on H2 and sulphate and on pyruvate. The results enable us to conclude that D. vulgaris Groningen contains a single hydrogenase of the [NiFe] type, located in the periplasmic space like that described for D. gigas. This enzyme appears to be involved in both H2 uptake and H2 production, depending on the growth conditions.
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PMID:Involvement of a single periplasmic hydrogenase for both hydrogen uptake and production in some Desulfovibrio species. 765 7

The reduction of CoM-S-S-HTP, the heterodisulfide of coenzyme M (H-S-CoM) and N-7-mercaptoheptanoylthreonine phosphate (H-S-HTP), with H2 is an energy-conserving step in methanogenic archaea. We report here that in Methanosarcina barkeri this reaction is catalyzed by a membrane-bound multienzyme complex, designated H2:heterodisulfide oxidoreductase complex, which was purified to apparent homogeneity. The preparation was found to be composed of nine polypeptides of apparent molecular masses 46 kDa, 39 kDa, 28 kDa, 25 kDa, 23 kDa, 21 kDa, 20 kDa, 16 kDa, and 15 kDa and to contain 3.2 nmol cytochrome b, 70 to 80 nmol non-heme iron and acid-labile sulfur, 5 nmol Ni, and 0.6 nmol FAD per mg protein. The 23 kDa polypeptide possessed heme-derived peroxidase activity indicating that this polypeptide is the cytochrome b. The purified H2:heterodisulfide oxidoreductase complex catalyzed the reduction of CoM-S-S-HTP with H2 at a specific activity of 6 U/mg protein (1 U = 1 mumol.min-1), the reduction of benzylviologen with H2 at a specific activity of 66 U/mg protein and the reduction of CoM-S-S-HTP benzylviologen with H2 at a specific activity of 66 U/mg protein and the reduction of CoM-S-S-HTP HTP with reduced benzylviologen at a specific activity of 24 U/mg protein. The complex did not mediate the reduction of coenzyme F420 with H2 nor the oxidation of reduced coenzyme F420 with CoM-S-S-HTP. The reduced cytochrome b in the enzyme complex could be oxidized by CoM-S-S-HTP and re-reduced by H2. The specific rates of cytochrome oxidation and reduction were too high to be resolved under our experimental conditions. The findings suggest that the H2:heterodisulfide oxidoreductase complex is composed of a F420-non-reducing hydrogenase, a cytochrome b and heterodisulfide reductase and that cytochrome b is a redox carrier in the electron transport chain involved in CoM-S-S-HTP reduction with H2.
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PMID:Purification of a cytochrome b containing H2:heterodisulfide oxidoreductase complex from membranes of Methanosarcina barkeri. 847 25