Fig. 1.
Partial reactions of the PDHC. The PDHC catalyzes the oxidative decarboxylation of pyruvate to form acetyl CoA. The enzyme complex is composed of three major subunits: pyruvate dehydrogenase (E1), dihydrolipoyl transacetylase (E2), and dihydrolipoyl dehydrogenase (E3). In addition to pyruvate and coenzyme A (CoASH), PDHC also requires a host of cofactors, including thiamine pyrophosphate (TPP), nicotinamide adenine dinucleotide (NAD+), flavin adenine dinucleotide (FAD), and lipoic acid (LIP).