Substrate stereochemistry of 2-methyl-branched-chain acyl-CoA dehydrogenase: elimination of one hydrogen each from (pro-2S)-methyl and alpha-methine of isobutyryl-CoA.
Dehydrogenation of (2S)-[3-13C]isobutyryl-CoA was carried out in vitro using 2-methyl-branched-chain acyl-CoA dehydrogenase purified from rat liver mitochondria. The product was subsequently hydrated by the addition of bovine crotonase. The resulting 3-hydroxyisobutyric acid was predominantly enriched with 13C at the beta-hydroxy position as determined as a methyl ester using electron ionization-gas chromatography-mass spectroscopy. This finding indicates that isobutyryl-CoA is dehydrogenated stereospecifically at the (pro-2S)-methyl and alpha-methine groups to form methacrylyl-CoA, which is later hydrated with the addition of hydrogen on the same side of the molecule from which it was subtracted to produce 3-hydroxyisobutyryl-CoA.
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry; D006885:Hydroxybutyrates / Q000378:metabolism; D008745:Methylation; D008930:Mitochondria, Liver / Q000201:enzymology; D008968:Molecular Conformation; D010088:Oxidoreductases / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors; D051381:Rats
D000214:Acyl Coenzyme A; D006885:Hydroxybutyrates; C050106:isobutyryl-coenzyme A; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C038808:2-methylacyl-CoA dehydrogenase; C020757:3-hydroxyisobutyric acid