Translations:Thiamine/10/en

Thiamine pyrophosphate

Main article: thiamine pyrophosphate

Thiamine pyrophosphate (TPP)

The ylide form of TPP

Thiamine pyrophosphate (TPP), also called thiamine diphosphate (ThDP), participates as a coenzyme in metabolic reactions, including those in which polarity inversion takes place. Its synthesis is catalyzed by the enzyme thiamine diphosphokinase according to the reaction thiamine + ATP → TPP + AMP (EC 2.7.6.2). TPP is a coenzyme for several enzymes that catalyze the transfer of two-carbon units and in particular the dehydrogenation (decarboxylation and subsequent conjugation with coenzyme A) of 2-oxoacids (alpha-keto acids). The mechanism of action of TPP as a coenzyme relies on its ability to form an ylide. Examples include:

• Present in most species
  • pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase (also called α-ketoglutarate dehydrogenase)
  • branched-chain α-keto acid dehydrogenase
  • 2-hydroxyphytanoyl-CoA lyase
  • transketolase
• Present in some species:
  • pyruvate decarboxylase (in yeast)
  • several additional bacterial enzymes