title: Direct demonstration of enol-oxaloacetate as an immediate product of malate oxidation by the mammalian succinate dehydrogenase.
abstract: Rapid malonate-sensitive transitory formation of enol-oxaloacetate followed by slow ketonization of the product was observed after addition of malate to the mammalian succinate-ubiquinone reductase in the presence of electron acceptor. The initial rate of enol-oxaloacetate production was equal to that of malate oxidation. Oxaloacetate keto-enol tautomerase had no effect on the initial rate of enol-oxaloacetate production nor on the kinetics of malate oxidation; the enzyme drastically accelerated the ketonization of the product. The solubilized and partially purified membrane-bound flavine adenine dinucleotide-dependent malate dehydrogenase from Acetobacter xylinum catalyzed oxidation of L- and D-malate without formation of enol-oxaloacetate as an intermediate of the reaction.
authors.affiliation: Department of Biochemistry, School of Biology, Moscow State University, USSR.
authors.forename: M V
authors.initials: MV
authors.lastname: Panchenko
authors.forename: A D
authors.initials: AD
authors.lastname: Vinogradov
mesh_terms: D000091:Acetobacter / Q000201:enzymology; D000818:Animals; D002417:Cattle; D007700:Kinetics; D008291:Malate Dehydrogenase / Q000378:metabolism; D008293:Malates / Q000378:metabolism*; D010071:Oxaloacetates / Q000378:metabolism*; D010084:Oxidation-Reduction; D013057:Spectrum Analysis; D013385:Succinate Dehydrogenase / Q000378:metabolism*
chemical_list: D008293:Malates; D010071:Oxaloacetates; C030298:malic acid; D008291:Malate Dehydrogenase; D013385:Succinate Dehydrogenase