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  • 1
    Electronic Resource
    Electronic Resource
    Purification and characterization of ferredoxin from Peptostreptococcus productus (strain Marburg) (1991)
    Springer
    Archives of microbiology 156 (1991), S. 422-426 
    Details
    ISSN: 1432-072X
    Keywords: Peptostreptococcus productus (strain Marburg) ; Homoacetogenic bacteria ; Ferredoxin ; Carbon monoxide dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248721
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamics of methylenetetrahydrofolate reduction to methyltetrahydrofolate and its implications for the energy metabolism of homoacetogenic bacteria (1991)
    Springer
    Archives of microbiology 155 (1991), S. 378-381 
    Details
    ISSN: 1432-072X
    Keywords: Methylenetetrahydrofolate ; Methyltetrahydrofolate ; Methylenetetrahydrofolate reductase ; Homoacetogenic bacteria ; Energy conservation of homoacetogens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00243458
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  • 3
    Electronic Resource
    Electronic Resource
    Acetate formation from CO and CO2 by cell extracts of Peptostreptococcus productus (strain Marburg) (1991)
    Springer
    Archives of microbiology 156 (1991), S. 75-80 
    Details
    ISSN: 1432-072X
    Keywords: Homoacetogenic bacteria ; Acetate synthesis from CO ; Carbon monoxide dehydrogenase ; Carbonylation reaction ; Peptostreptococcus productus (strain Marburg) ; Tetrahydrofolate enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00418191
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  • 4
    Electronic Resource
    Electronic Resource
    Studies on tetrachloroethene respiration inDehalospirillum multivorans (1996)
    Springer
    Archives of microbiology 166 (1996), S. 379-387 
    Details
    ISSN: 1432-072X
    Keywords: Dehalospirillum multivorans ; Reductive dechlorination ; Tetrachloroethene respiration ; Trichloroethene ; PCE dehalogenase ; Formate dehydrogenase ; Fumarate respiration ; Hydrogenase ; Electron transport chain ; Reversed electron flow ; Ferredoxin ; Menaquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tetrachloroethene (PCE) respiration was studied in the tetrachloroethene-utilizing anaerobe,Dehalospirillum multivorans, with respect to localization of the catabolic enzymes, the electron carriers potentially involved in electron transport, and the response to ionophores and specific inhibitors. Hydrogenase and formate dehydrogenase were recovered in the periplasmic cell fraction and were membrane-associated. Electron-accepting tetrachloroethene dehalogenase was found in the cytoplasmic fraction. In the PCE dehalogenase assay, only artificial electron donors with a standard redox potential of 〈-360 mV were effective electron donors for PCE reduction. Besides these artificial reductants, ferredoxin isolated fromD. multivorans (E′o=-445 mV) could serve as electron donor for PCE reduction. However, the reaction rate with ferredoxin was only 1% of that with methyl viologen, whereas the pyruvate-ferredoxin oxidoreductase exhibited almost the same reaction rates with methyl viologen and ferredoxin as electron acceptors for pyruvate oxidation. Reduced menadione (2-methyl-1,4-naphthoquinone) did not serve as electron donor in the PCE dehalogenase reaction. 2-Heptyl-4-hydroxyquinoline-N-oxide (HOQNO) had no significant effect on PCE dechlorination in cell suspensions and in crude extracts. Whole cells catalyzed the reductive dechlorination of PCE with H2 or formate as electron donors. The dechlorination in cell suspensions rather than in cell extracts was inhibited by the ionophores carbonylcyanide-p-(trifluoromethoxy)-phenylhydrazone (FCCP) and tetrachlorosalicylanilide (TCS), indicating that a membrane potential and/or a pH gradient may be required for the reaction in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01682983
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  • 5
    Electronic Resource
    Electronic Resource
    Properties of tetrachloroethene and trichloroethene dehalogenase of Dehalospirillum multivorans (1995)
    Springer
    Archives of microbiology 163 (1995), S. 276-281 
    Details
    ISSN: 1432-072X
    Keywords: Tetrachloroethene ; Trichloroethene ; Dichloroethene ; PCE dehalogenase ; TCE dehalogenase ; Corrinoid ; Vitamin B12 ; Dehalospirillum multivorans ; Reductive dechlorination ; Tetrachloroethene respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Some properties of tetrachloroethene and trichloroethene dehalogenase of the recently isolated, tetrachloroethene-utilizing anaerobe, Dehalospirillum multivorans, were studied with extracts of cells grown on pyruvate plus fumarate. The dehalogenase catalyzed the oxidation of reduced methyl viologen with tetrachloroethene (PCE) or trichloroethene (TCE) as electron acceptor. All other artificial or physiological electron donors tested were ineffective. The PCE and TCE dehalogenase activity was insensitive towards oxygen in crude extracts. When extracts were incubated under anoxic conditions in the presence of titanium citrate as reducing agent, the dehalogenase was rapidly inactivated by propyl iodide (50 μM). Inactivation did not occur in the absence of titanium citrate. The activity of propyl-iodide-treated extracts was restored almost immediately by illumination. The dehalogenase was inhibited by cyanide. The inhibition profile was almost the same under oxic and anoxic conditions independent of the presence or absence of titanium citrate. In addition, N2O, nitrite, and ethylene diamine tetra-acetate (EDTA) were inhibitors of PCE and TCE dehalogenase. Carbon monoxide and azide had no influence on the dehalogenase activity. Trans-1,2-dichloroethene or 1,1-dichloroethene, both of which are isomers of the dechlorination product cis-1,2-dichloroethene, neither inhibited nor inactivated the dehalogenase. PCE and TCE dechlorination appeared to be mediated by the same enzyme since the inhibitors tested had nearly the same effects on the PCE and TCE dehalogenating activity. The data indicated the involvement of a corrinoid and possibly of an additional transition metal in reductive PCE and TCE dechlorination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393380
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  • 6
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a methyl chloride utilizing, strictly anaerobic bacterium (1991)
    Springer
    Archives of microbiology 156 (1991), S. 416-421 
    Details
    ISSN: 1432-072X
    Keywords: Methyl chloride utilization ; Homoacetogenic bacteria ; Anaerobic dehalogenation ; Strain MC ; Methylotrophic anaerobes ; Methoxylated aromatic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248720
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  • 7
    Electronic Resource
    Electronic Resource
    Methyl chloride metabolism of the strictly anaerobic, methyl chloride-utilizing homoacetogen strain MC (1993)
    Springer
    Archives of microbiology 160 (1993), S. 383-387 
    Details
    ISSN: 1432-072X
    Keywords: Homoacetogenic bacteria ; Acetate formation from methyl chloride ; Strain MC ; Tetrahydrofolate enzymes ; Methyl tetrahydrofolate foramtion ; Anaerobic dechlorination ; O-demethylation of methoxylated aromatics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00252225
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