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  • 1
    ISSN: 1432-072X
    Schlagwort(e): Peptostreptococcus productus (strain Marburg) ; Homoacetogenic bacteria ; Ferredoxin ; Carbon monoxide dehydrogenase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Ferredoxin was purified to apparent homogeneity from cell extracts of the homoacetogen Peptostreptococcus productus (strain Marburg). The yield was 70 μg ferredoxin per g wet cells of P. productus. The UV-vis spectrum exhibited characteristics of a typical clostridial ferredoxin spectrum with a molar extinction coefficient ε385 of ∼30000 M-1 cm-1 and an A385/A280 ratio of 0.76. The molecular weight Mr was near 5700 as calculated from the amino acid composition. The protein contained per mol 9.9 mol iron, 8.2 mol acid-labile sulfide, and near 7 mol cysteine indicating the presence of two 4 Fe/4 S clusters. The redox potential was determined to be-410 mV. The purified ferredoxin was reduced with carbon monoxide by the carbon monoxide dehydrogenase from crude extracts and by the partially enriched enzyme of P. productus.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 156 (1991), S. 416-421 
    ISSN: 1432-072X
    Schlagwort(e): Methyl chloride utilization ; Homoacetogenic bacteria ; Anaerobic dehalogenation ; Strain MC ; Methylotrophic anaerobes ; Methoxylated aromatic compounds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract From sludge obtained from the sewage digester plant in Stuttgart-Möhringen a strictly anaerobic bacterium was enriched and isolated with methyl chloride as the energy source. The isolate, which was tentatively called strain MC, was nonmotile, gram-positive, and occurred as elongated cocci arranged in chains. Cells of strain MC formed about 3 mol of acetate per 4 mol of CH3Cl consumed, indicating that the organism was a homoacetogenic bacterium fermenting methyl chloride plus CO2 according to: $$\begin{gathered} 4 CH_3 Cl + 2 CO_2 + 2 H_2 O \to 3 CH_3 COO^ - \hfill \\ + 7 H^ + + 4 Cl^ - . \hfill \\ \end{gathered} $$ The organism grew with 2–3% methyl chloride in the gas phase at a doubling time of near 30 h. Dichloromethane was not utilized. The bacterium also grew on carbon monoxide, H2 plus CO2, and methoxylated aromatic compounds. Optimal growth with methyl chloride was observed at 25°C and pH 7.3–7.7. The G+C-content of the DNA was 47.5±1.5%. The methyl chloride conversion appeared to be inducible, since H2 plus CO2-grown cells lacked this ability. From the morphological and physiological characteristics, the isolate could not be affiliated to a known species.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-072X
    Schlagwort(e): Methylenetetrahydrofolate ; Methyltetrahydrofolate ; Methylenetetrahydrofolate reductase ; Homoacetogenic bacteria ; Energy conservation of homoacetogens
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The thermodynamics of the methylenetetrahydrofolate reduction to 5-methyltetrahydrofolate was studied with the methylenetetrahydrofolate reductase purified from the homoacetogenic bacterium Peptostreptococcus productus. The equilibrium constants were determined for the forward and backward reactions of methylenetetrahydrofolate reduction with NADH or acetylpyridine adenine dinucleotide (APADH), respectively, as the electron donors. From the equilibrium constants and the known standard redox potentials at pH 7 (E o′ ) of the couples NAD+/NADH or APAD+/APADH the E o′ of the couple methylene-/methyltetrahydrofolate was determined to be about-200mV. This value is different from values reported before for this couple. The implications for the mechanism of energy conservation of homoacetogens is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 156 (1991), S. 75-80 
    ISSN: 1432-072X
    Schlagwort(e): Homoacetogenic bacteria ; Acetate synthesis from CO ; Carbon monoxide dehydrogenase ; Carbonylation reaction ; Peptostreptococcus productus (strain Marburg) ; Tetrahydrofolate enzymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cell extracts of Peptostreptococcus productus (strain Marburg) obtained from CO grown cells mediated the synthesis of acetate from CO plus CO2 at rates of 50 nmol/min × mg of cell protein. 14CO was specifically incorporated into C1 of acetate. No label exchange occurred between 14C1 of acetyl-CoA and CO, indicating that 14CO incorporation into acetate was by net synthesis rather than by an exchange reaction. In acetate synthesis from CO plus CO2 the latter substrate could be replaced to some extent by formate or methyl tetrahydrofolate as the methyl donor. The methyl group of methyl cobalamin was incorporated into acetate ony at very low activities. The cell extracts contained high levels of enzyme activities involved in acetate or cell carbon synthesis from CO2. The following enzymic activities were detected: CO: methyl viologen oxidoreductase, formate dehydrogenase, formyl tetrahydrofolate synthetase, methenyl tetrahydrofolate cyclohydrolase, methylene tetrahydrofolate dehydrogenase, methylene tetrahydrofolate reductase, phosphate acetyltransferase, acetate kinase, hydrogenase, NADPH: benzyl viologen oxidoreductase, and pyruvate synthase. Some kinetic and other properties were studied.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 160 (1993), S. 383-387 
    ISSN: 1432-072X
    Schlagwort(e): Homoacetogenic bacteria ; Acetate formation from methyl chloride ; Strain MC ; Tetrahydrofolate enzymes ; Methyl tetrahydrofolate foramtion ; Anaerobic dechlorination ; O-demethylation of methoxylated aromatics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The methyl chloride metabolism of the homoacetogenic, methyl chloride-utilizing strain MC was investigated with cell extracts and cell suspensions of the organism. Cell extracts were found to contain all enzyme activities required for the conversion of methyl chloride or of H2 plus CO2 to acetate. They catalyzed the dechlorination of methyl chloride with tetrahydrofolate as the methyl acceptor at a rate of ∼20 nmol/min × mg of cell protein. Also, the O-demethylation of vanillate with tetrahydrofolate could be measured at a rate of 40 nmol/min × mg. Different enzyme systems appeared to be responsible for the dehalogenation of CH3Cl and for the O-demethylation of methoxylated aromatic compounds, since cells grown with methoxylated aromatic compounds exhibited a significantly lower activity of CH3Cl conversion than methyl chloride grown cells and vice versa. In addition, ammonium thiocyanate (5 mM) completely inhibited CH3Cl dechlorination, whereas the consumption of vanillate was not affected significantly. The data were taken to indicate, that the methyl chloride dehalogenation is catalyzed by a specific, inducible enzyme present in strain MC, and that tetrahydrofolate rather than the corrinoid-protein involved in acetate formation is the primary acceptor of the methyl group in the dechlorination reaction.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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