Transketolase (TKT)

Transketolase (EC 2.2.1.1) is a thiamine-dependent enzyme that links the pentose phosphate pathway with the glycolytic pathway. The pentose phosphate pathway, which is active in most tissues, provides sugar phosphates for intermediary biosynthesis, especially nucleotide metabolism, and generates the biosynthetic reducing power for the cell in the form of NADPH.

Transketolase is directly involved in the branch of the pathway that channels excess sugar phosphates to glycolysis, enabling the production of NADPH to be maintained under different metabolic conditions. NADPH is critical for maintaining cerebral glutathione, and thus it is likely that transketolase plays an important role in brain metabolism.