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. © 1991.
Panchenko, M. V., & Vinogradov, A. D. (1991). Direct demonstration of enol-oxaloacetate as an immediate product of malate oxidation by the mammalian succinate dehydrogenase. FEBS Letters, 286(1–2), 76–78. https://doi.org/10.1016/0014-5793(91)80944-X