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  • 1
    ISSN: 1432-072X
    Keywords: Key words Electron transport phosphorylation ; Respiration ; Membrane vesicles ; Anaerobic degradation ; Glyoxylate ; Glycolate ; Hydrogen ; Syntrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The syntrophically glycolate-fermenting bacterium in the methanogenic binary coculture FlGlyM was isolated in pure culture (strain FlGlyR) with glyoxylate as sole substrate. This strain disproportionated 12 glyoxylate to 7 glycolate, 10 CO2, and 3 hydrogen. Glyoxylate was oxidized via the malyl-CoA pathway. All enzymes of this pathway, i.e. malyl-CoA lyase/malate: CoA ligase, malic enzyme, and pyruvate synthase, were demonstrated in cell-free extracts. Glycolate dehydrogenase, hydrogenase, and ATPase, as well as menaquinones as potential electron carriers, were present in the membranes. Everted membrane vesicles catalyzed hydrogen-dependent glyoxylate reduction to glycolate [86–207 nmol min–1 (mg protein)–1] coupled to ATP synthesis from ADP and Pi [38–82 nmol min–1 (mg protein)–1)]. ATP synthesis was abolished entirely by protonophores or ATPase inhibitors (up to 98 and 94% inhibition, respectively) indicating the involvement of proton-motive force in an electron transport phosphorylation driven by a new glyoxylate respiration with hydrogen as electron donor. Measured reaction rates in vesicle preparations revealed a stoichiometry of ATP formation of 0.2–0.5 ATP per glyoxylate reduced.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 164 (1995), S. 271-279 
    ISSN: 1432-072X
    Keywords: Key words Dissimilatory sulfate reduction ; Glycolate Incomplete oxidation ; Desulforubidin ; Glycolate ; dehydrogenase ; CO dehydrogenase ; Menaquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sulfate-dependent degradation of glycolate was studied with a new sulfate-reducing bacterium, strain PerGlyS, enriched and isolated from marine anoxic sediment. Cells were gram-negative, motile rods with a DNA G+C content of 56.2 ± 0.2 mol%. Cytochromes of the b- and c-type and menaquinone-5 were detected. A sulfite reductase of the desulforubidin-type was identified by characteristic absorption maxima at 279, 396, 545, and 580 nm. The purified desulforubidin is a heteropolymer consisting of three subunits with molecular masses of 42.5 (α), 38.5 (β), and 13 kDa (γ). Strain PerGlyS oxidized glycolate completely to CO2. Lactate, malate, and fumarate were oxidized incompletely, yielding more sulfide and less acetate than expected for typical incomplete oxidation of these substrates. Part of the acetate residues formed was oxidized through the CO-dehydrogenase pathway. The biochemistry of glycolate degradation was investigated in cell-free extracts. A membrane-bound glycolate dehydrogenase, but no glyoxylate-metabolizing enzyme activity was detected; the further degradation pathway is unclear.
    Type of Medium: Electronic Resource
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