| Definition: |
The chemical reactions and pathways resulting in the formation of a branched-chain acyl-CoA by the oxidative decarboxylation of a branched-chain alpha-keto acid derived from L-leucine, L-isoleucine or L-valine. This pathway comprises a series of three reactions carried out by a multisubunit complex called the 'branched-chain alpha-keto acid dehydrogenase complex', even though branched-chain alpha-keto acid dehydrogenase activity describes only one of those reactions. The combination of the three reactions can be summarized as: 3-methyl-2-oxobutanoate + coenzyme A + NAD+ -> branched-chain acyl-CoA + CO2 + NADH. Specific substrates include 3-methyl-2-oxobutanoate (a transamination product of L-valine), (S)-3-methyl-2-oxopentanoate (a transamination product of L-isoleucine) and 4-methyl-2-oxopentanoate (a transamination product of L-leucine), which generate the products 2-methylpropanoyl-CoA, 2-methylbutanoyl-CoA and 3-methylbutanoyl-CoA, respectively. |