Pyruvate dehydrogenase is the first component enzyme of pyruvate dehydrogenase complex (PDC). The pyruvate dehydrogenase complex contributes to transforming pyruvate into acetyl-CoA by a process called pyruvate decarboxylation. Acetyl-CoA may then be used in the citric acid cycle to carry out cellular respiration, so pyruvate dehydrogenase contributes to linking theglycolysis metabolic pathway to the citric acid cycle and releasing energy via NADH.Pyruvate dehydrogenase performs the first two reactions within the pyruvate dehydrogenase complex (PDC): a decarboxylation of substrate 1 (pyruvate) and a reductive acetylation of substrate 2 (lipoic acid). Lipoic acid is covalently bound to dihydrolipoamide acetyltransferase, which is the second catalytic component enzyme of PDC. The reaction catalyzed by pyruvate dehydrogenase is considered to be the rate-limiting step for the pyruvate dehydrogenase complex (PDHc).