Abstract
Thiamine diphosphate (ThDP), the biologically active form of thiamine (vitamin B1), functions as a cofactor in enzymes that catalyse various essential reactions in metabolic pathways. The ThDP-dependent enzymes are ubiquitously present in all organisms and generally catalyse oxidative conversion or the nonoxidative transfer of 2-keto acids. The first essential activation step common in all ThDP-dependent enzymes is the formation of ThDP ylide. The ThDP ylide is a C2 ionized state of the thiazolium ring that attacks the substrate carbonyl group. Pyruvate decarboxylase, pyruvate oxidase, pyruvate:ferredoxin oxidoreductase and pyruvate dehydrogenase catalyse different reactions after the decarboxylation of pyruvate. Transketolase catalyses transfer of a two-carbon fragment between sugar phosphates, whereas phosphoketolase catalyses phosphorolytic cleavage of sugar phosphates. The ThDP-dependent enzymes are classified into five families.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
