REACTIONS catalyzed by pyruvic dehydrogenase.The reactions catalyzed by pyruvic dehydrogenase require the PARTICIPATION of several coenzymes, including NAD+ and Coenzyme A. This process is called Link reaction or gateway reaction.During this process, two molecules of NADH are produced from the metabolism of two molecules of pyruvic acid (produced from one glucose molecule during glycolysis)The acetyl CoA then enters a cyclic pathway, the citric acid cycle more commonly called Krebs’ cycle after the scientist Hans Krebs who first elucidated it.Thus, Pyruvic acid before COMBINING with oxaloacetic acid of the citric acid cycle becomes Acetyl CoA Under anaerobic CONDITIONS, the pyruvic acid undergoes partial oxidation to form lactic acid. This process is catalyzed by the enzyme lactate dehdrogenaseDuring the Kreb's cycle, Acetyl CoA condenses with Oxaloacetic acid to form Citric acid. This Citric acid is then CONVERTED into Cis Aconitic acid in the presence of enzyme Aconitase.