1. [14C]Acetoin was enzymically synthesized from [14C]pyruvate with a pyruvate decarboxylase preparation. Its optical activity was [α]20d-78°. 2. Large amounts (1000-fold higher than physiological concentrations) of acetoin were incubated with rat liver mince. Acetoin disappeared but very little 14CO2 was evolved. A compound accumulated, which was purified and identified as butane-2,3-diol. Chromatography on borate-impregnated paper indicated the presence of both the erythro and threo forms. 3. Liver extracts capable of interconverting biacetyl, acetoin and butane-2,3-diol were obtained. These interconversions were catalysed by two different enzymes: acetoin dehydrogenase (EC 188.8.131.52) and butane-2,3-diol dehydrogenase (EC 184.108.40.206), previously identified in bacteria. Both required NAD+ or NADP+ as cofactors and were different from alcohol dehydrogenase. The equilibrium in both cases favoured the more reduced compound. 4. The activity of butane-2,3-diol dehydrogenase was decreased by dialysis against EDTA: the addition of Co2+, Cu2+, Zn2+ and other bivalent metal ions restored activity. 5. Biacetyl reductase was resolved into multiple forms by CM-Sephadex chromatography and electrophoresis.
Metabolism of acetoin in mammalian liver slices and extracts. Interconversion with butane-2,3-diol and biacetyl
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M. A. Gabriel, Haifa Jabara, U. A. S. Al-Khalidi; Metabolism of acetoin in mammalian liver slices and extracts. Interconversion with butane-2,3-diol and biacetyl. Biochem J 1 October 1971; 124 (4): 793–800. doi: https://doi.org/10.1042/bj1240793
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