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

Mechanical disruption of cells of Methanobacterium strain G2R resulted in a 78-fold increase in the specific activity of the hydrogenase as measured by the benzyl viologen reduction assay. Approximately 50% of the activity in disrupted cells was associated with the particulate fraction. Between 69 and 85% of the particulate hydrogenase was released by treatment with the detergents Triton X-100, deoxycholate, and octyl-beta-d-glucopyranoside. The relative electrophoretic mobilities of the soluble hydrogenases were identical, indicating that G2R possessed a single electrophoretically distinct hydrogenase. The particulate enzyme was inactivated by oxygen and could be reactivated with dithionite or glucose plus glucose oxidase. The enzyme had a pH optimum of 8.5 and resisted heating at 52 but not 77 degrees C. A number of nonspecific dyes, flavin adenine dinucleotide, and riboflavin 5'-phosphate were effective electron acceptors; oxidized nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide phosphate, and factor 420 were apparently not reduced. Hydrogenase activity was inhibited by p-hydroxymercuribenzoate, cyanide, chloroform, and chloramphenicol. The molecular weight of the solubilized enzyme was 900,000, with subunits of molecular weights 38,500, 50,700, and approximately 80,000. It is suggested that, in intact cells of G2R, the large hydrogenase complex is loosely bound to the cell wall or membrane.
 ...
PMID:Solubilization and properties of a particulate hydrogenase from Methanobacterium strain G2R. 3 36

Bartha, R. (University of Washington, Seattle), and E. J. Ordal. Nickel-dependent chemolithotrophic growth of two Hydrogenomonas strains. J. Bacteriol. 89:1015-1019. 1965.-The trace element requirements for growth of facultative chemolithotrophic Hydrogenomonas strains H1 and H16 were investigated under both autotrophic and heterotrophic conditions. The organisms were grown in a mineral medium, rendered deficient in trace elements by extraction with 8-hydroxyquinoline and chloroform, and, in some cases, by coprecipitation with copper. The organic substrates, succinate and fumarate, used for heterotrophic growth were treated in a similar fashion. Acetate and butyrate were purified by redistillation. It was found that iron alone was required for heterotrophic growth (optimal concentration, 1.5 x 10(-6)m Fe(+++)), but cells grown chemolithotrophically on molecular hydrogen required the addition of nickel. The yield of protein was proportional to the nickel added, reaching a maximum at 3 x 10(-7)m Ni(++). Manganese, cobalt, copper, and zinc, alone or in combination, failed to substitute for nickel in the experiments with Hydrogenomonas. Although nickel is required specifically for the chemolithotrophic growth of Hydrogenomonas, nickel deficiency did not affect: (i) the synthesis or activation of hydrogenase, (ii) the Knallgas reaction, (iii) the assimilation of CO(2) by resting cells, or the synthesis of the storage material poly-beta-hydroxybutyric acid. It is suggested that nickel participates in some reaction involved in CO(2) fixation by growing cells.
 ...
PMID:NICKEL-DEPENDENT CHEMOLITHOTROPHIC GROWTH OF TWO HYDROGENOMONAS STRAINS. 1427 88

Fukuyama, T. (University of Washington, Seattle), and E. J. Ordal. Induced biosynthesis of formic hydrogenlyase in iron-deficient cells of Escherichia coli. J. Bacteriol. 90:673-680. 1965.-Escherichia coli cells were grown aerobically on a lactate-mineral salts medium from which iron had been removed by extraction with 8-hydroxyquinoline and chloroform. These cells carried out induced biosynthesis of formic hydrogenlyase in a reaction mixture containing glucose, formate, and phosphate without the addition of amino acids, providing adequate amounts of iron salts were present. In the absence of iron, glucose was fermented and acids were produced, but no formic hydrogenlyase developed. When iron-deficient E. coli cells were repeatedly washed, the property of carrying out induced biosynthesis of formic hydrogenlyase with glucose, formate, phosphate, and iron was lost, but was restored on addition of acid-hydrolyzed casein to the reaction mixture. An energy source (provided as glucose) was necessary for enzyme production. Iron-deficient cells were devoid of hydrogenase and formic hydrogenlyase but showed formic dehydrogenase activity when adequate amounts of selenium and molybdenum were present in the growth medium. Hydrogenase was consistently absent in iron-deficient cells but appeared concomitantly with formic hydrogenlyase during induced biosynthesis of the latter in iron-deficient cells of E. coli.
 ...
PMID:Induced Biosynthesis of Formic Hydrogenlyase in Iron-Deficient Cells of Escherichia coli. 1656 66

Hydrogenase (hydrogen:ferricytochrome c(3) oxidoreductase, EC 1.12.2.1) from Desulfovibrio vulgaris was encapsulated in reversed micelles with cetyltrimethylammonium bromide as surfactant and a chloroform/octane mixture as solvent. Reducing equivalents for hydrogenase-catalyzed hydrogen production were provided by vectorial photosensitized electron transfer from a donor (thiophenol) in the organic phase through a surfactant-Ru(2+) sensitizer located in the interphase to methyl viologen concentrated in the aqueous core of the reversed micelle. The results show that reversed micelles provide a microenvironment that (i) stabilizes hydrogenase against inactivation and (ii) allows an efficient vectorial photosensitized electron and proton flow from the organic phase to hydrogenase in the aqueous phase.
 ...
PMID:Photosensitized production of hydrogen by hydrogenase in reversed micelles. 1659 4

Batch culture conditions were established for the formation of H(2)-driven whole-cell soluble or particulate methane monooxygenase (sMMO or pMMO) activity in the obligate methanotroph, Methylosinus trichosporum Ob3b, to expand its potential uses in groundwater bioremediation and the production of specific chemicals. Addition of either Ni and H(2) to a nitrate-containing minimal salts growth medium or Ni and Mo to a nitrate-lacking growth medium (induces a nitrogenase that generates intracellular H(2)) markedly enhanced both the hydrogenase and the accompanying washed-cell H(2)-driven MMO activities of shake-flask cultured cells. For sMMO containing cells, H(2) provided in vitro reducing power for the oxidation of chlorinated solvents such as chloroform and trichloroethylene. Cell cultivations under N(2)-fixing conditions in a 5-L bioreactor, however, required an initial nitrate concentration of at least 1 to 2 mM to achieve high biomass yields (5 to 7 g of dry cell wt/L) for cells producing H(2)-driven sMMO or pMMO activity. Elevation of the initial medium nitrate concentration to 20 mM shortened the culture time for pMMO producing cells by 40%, yet still generated an equivalent growth yield. High nitrate also shortened the culture time for sMMO containing cells by approximately 25%, but it lowered their biomass yield by 26%. Upon storage for 5 weeks at room temperature, washed resting-state cells retained 90% and 70% of their H(2)-driven sMMO and pMMO activity, respectively. This makes their practical use quite feasible. (c) 1995 John Wiley & Sons, Inc.
 ...
PMID:Batch cultivation of Methylosinus trichosporium OB3B: IV. Production of hydrogen-driven soluble or particulate methane monooxygenase activity. 1862 42