The pyruvate dehydrogenase complex catalyzes the overall conversion of pyruvate to acetyl-CoA and CO(2). It contains multiple copies of three enzymatic components: pyruvate dehydrogenase (E1), dihydrolipoamide acetyltransferase (E2) and lipoamide dehydrogenase (E3) (By similarity). (R)-N(6)-lipoyl-L-lysyl-[dihydrolipoyllysine-residue acetyltransferase] + H(+) + pyruvate = (R)-N(6)-(S(8)-acetyldihydrolipoyl)-L-lysyl-[dihydrolipoyllysine-residue acetyltransferase] + CO2 Binds 1 lipoyl cofactor covalently. Binds 1 thiamine pyrophosphate per subunit. Heterodimer of an alpha and a beta chain.