D-Lactate dehydrogenase of Peptostreptococcus elsdenii.
D-Lactate dehydrogenase has been purified to near homogeneity from Peptostreptococcus elsdenii. As isolated, the enzyme contains flavine adenine dinucleotide and a tightly bound metal cofactor. Inactivation by ortho-phenanthroline occurs in two steps and is partially blocked by D-lactate. Reactivation by divalent metal ions occurs, with divalent zinc being the most effective. When ferricyanide is used as the electron acceptor, D-lactate has an apparent K0.5 of 3.3 M0.46; its binding is negatively cooperative with a Hill coefficient of 0.46. Replacement of ferricyanide by the other components of the electron transport system yields hyperbolic kinetics with an apparent Km for D-lactate of 26 mM. The apparent Km for ferricyanide is 2.2 X 10(-4) M. Phosphate and pyrophosphate compounds stimulate the D-lactate:ferricyanide activity. These properties suggest that interaction of this enzyme with other electron transport proteins in the chain may enhance D-lactate binding and, hence, the rate of electron transport.
D002474:Cell-Free System; D004579:Electron Transport; D004789:Enzyme Activation; D005292:Ferricyanides / Q000378:metabolism; D005420:Flavoproteins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006885:Hydroxybutyrates / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000302:isolation & purification / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D008670:Metals / Q000494:pharmacology; D010084:Oxidation-Reduction; D010462:Peptostreptococcus / Q000201:enzymology; D010618:Phenanthrolines / Q000494:pharmacology; D010710:Phosphates / Q000494:pharmacology; D013237:Stereoisomerism; D015032:Zinc / Q000494:pharmacology
D005292:Ferricyanides; D005420:Flavoproteins; D006885:Hydroxybutyrates; D007773:Lactates; D008670:Metals; D010618:Phenanthrolines; D010710:Phosphates; D007770:L-Lactate Dehydrogenase; D015032:Zinc