Cellular component

BCKD complex, BKDH complex

A multi-enzyme complex that catalyzes the oxidative decarboxylation of branched-chain alpha-ketoacids derived from L-leucine, L-isoleucine, and L-valine to branched-chain acyl-CoAs. The complex comprises multiple copies of three enzymes referred to as E1, E2 and E3: branched-chain alpha-ketoacid dehydrogenase (E1, a heterotetramer of two alpha and two beta subunits), dihydrolipoyl transacylase (E2), and dihydrolipoamide dehydrogenase (E3). Additional proteins may also be present.

The catalytic activities of the individual components of this complex are represented by the molecular function terms '3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring) activity ; GO:0003863' (E1), 'dihydrolipoyllysine-residue (2-methylpropanoyl)transferase activity ; GO:0043754' (E2), and 'dihydrolipoyl dehydrogenase activity ; GO:0004148' (E3). The overall catalytic activity of the complex is represented by the molecular function term 'branched-chain alpha-keto acid dehydrogenase activity (GO:0047101)'.