Pyruvate ferredoxin oxidoreductase and its radical intermediate

Pyruvate synthase, an enzyme that has the ability to perform the thiamine pyrophosphate (TPP)-dependent oxidative decarboxylation of pyruvate to form acetyl-CoA and CO2, is reviewed. First, the early steps leading to the formation of the two key intermediates, the ylide and the anionic 2α-hydroxyethylidene (TPP), are discussed. Following this, the factors that lead to a 10-fold rate enhancement for deprotonation of the C2-thiazolium proton and the C2α proton of HE-TPP are outlined. Finally, how the low-potential electrons from pyruvate decarboxylation are transferred to external acceptors is highlighted.