The Citric Acid Cycle. I wanted to know why the multi-protein PDH complex for the pyruvate decarboxylation process (that consists of E1 (Pyruvate Dehydrogenase), E2 (Dihydrolipoyl transacetylase), and E3 (Dihydrolipoyl dehydrogenase)) is more efficient than using independent enzymes to convert pyruvate to Acetyl-CoA.