Branched-chain keto acid dehydrogenases form the E1 component of the branched-chain alpha-ketoacid dehydrogenase complex (BCKDC), a multi-subunit complex that is found on the mitochondrial inner membrane and catalyzes the oxidative decarboxylation of branched, short-chain alpha-ketoacids. The E1 subunit uses thiamine pyrophosphate as a catalytic cofactor to catalyze both the decarboxylation of the alpha-ketoacid and the subsequent reductive acylation of the lipoyl moiety (another catalytic cofactor) that is covalently bound to the E2 component. In animal tissue, the BCKDC catalyzes an irreversible step in the catabolism of the branched-chain amino acids L-isoleucine, L-valine, and L-leucine. (Adapted from https://en.wikipedia.org/wiki/Branched-chain_alpha-keto_acid_dehydrogenase_complex.)
