quality:correction, linguistic:paraphrasing, structural:scholar_edition
Differences between oxidative decarboxylation and simple decarboxylation

During the reaction, E1 participates in the decarboxylation of pyruvic acid, and then TPP connects the acetyl group after the reaction. The carbonyl group of the acetyl group reacts with the carbonyl group of the carbon negative ion on the thiazole ring of TPP to form hydroxyethyl. Then, with the catalysis of E2, TPP sends the hydroxyethyl to lipoamide, which is reoxidized to acetyl to produce thioester bond. At this time, the compound is acetyl dihydrolipoamide, which is then catalyzed by E2, and acetyl is transferred, to form acetyl CoA, all the above reactions only involve decarboxylation reaction, and do not involve the movement of H, while the real dehydrogenation effect of pyruvate dehydrogenase system will be reflected in the next step of reaction. Acetyl dihydrolipoamide without acetyl group is lost, that is, dihydrolipoamide needs to be re oxidized to lipoamide to participate in the reaction again. At this time, E3 needs to participate in the catalytic reaction, and the hydrogen removed from dihydrolipoamide will be transferred to FAD to make it FADH2, FADH2 reacts with NAD+ to generate NADH and H+.