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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 88 (1973), S. 299-318 
    ISSN: 1432-072X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A new hydrogen bacterium has been isolated by enrichment culture on propane. It is a strictly aerobic, Gram-positive, non acid-fast bacterium, characterized by filamentous growth, and has been tentatively assigned to Nocardia opaca (strain 1 b). It grows heterotrophically, on many organic compounds (71 out of 138 tested substrates including organic acids and sugars), on hydrocarbons (C11−C18) as well as under autotrophic conditions (under an atmosphere of hydrogen, oxygen, and carbon dioxide=8:1:1) In the absence of a nitrogen source storage materials, mainly carbohydrates, are accumulated. Hydrogenase is an inducible enzyme. Under appropriate growth conditions the specific hydrogenase activity reaches high values: 2700 enzyme units/g cell protein. The formation of hydrogenase is repressed by fructose. With increasing oxygen concentrations during growth the specific hydrogenase activity decreases. In resting cell oxygen progressively inhibits the oxyhydrogen reaction. Cell-free extracts of autotrophically grown cells are able to reduce oxygen benzyl-and methyl viologen, dichlorphenolindophenol, methylene blue and nicotinamide adeninedinucleotide with hydrogen.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 100 (1974), S. 25-39 
    ISSN: 1432-072X
    Schlagwort(e): NAD-Dependent Hydrogenase ; Hydrogen Dehydrogenase ; Nocardia opaca Strain 1 b ; Hydrogen Bacteria ; Chemolithoautotrophic Bacteria ; Gram-Positive Hydrogen Bacteria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nocardia opaca strain 1 b has a NAD-dependent hydrogenase (hydrogen dehydrogenase). The enzyme has been purified from autotrophically grown cells and tested for optimal assay conditions and stability. The purification procedure involved protamine sulfate treatment, ammonium sulfate precipitation, and separation by DEAE-cellulose and Sephadex G-200 chromatography and resulted in a 63-fold increase of specific activity at a 11.7% enzyme recovery. The final specific activity was 103 μmoles H2/min·mg protein. The purified enzyme was dependent on nickel and magnesium ions at 0.5 and 5.0 mM concentrations, respectively, as well as flavin mononucleotide at a 5–10 μM concentration. Straight enzyme kinetics were achieved by preincubating the enzyme in the presence of NADH2. A high stability of the enzyme was observed in 0.1 M potassium phosphate buffer, pH 6.5, in the presence of 0.5 mM nickel and 5 mM magnesium ions under hydrogen atmosphere. Even under air the enzyme was remarkably stable, although less than under hydrogen. From double reciprocal plots of substrate saturation curves the Michaelis-Menten constants were calculated: For saturating NAD-concentration the K m was 0.063 mM H2 and for saturating hydrogen concentration the K m was 0.123 mM NAD.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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