Transketolase
Cofactors used
Clinical / pharmacological. TPP-dependent; erythrocyte transketolase activity assesses thiamine status
What it does, reaction by reaction
Pentose Phosphate Pathway (Oxidative and Non-oxidative phases) Carbohydrate Metabolism · Cytosol
Xylulose-5-phosphate + ribose-5-phosphate → glyceraldehyde-3-phosphate + sedoheptulose-7-phosphate
Converts Xylulose-5-phosphate Ribose-5-phosphate into Glyceraldehyde-3-phosphate Sedoheptulose-7-phosphate
› Notes
Transketolase transfers a two-carbon glycolaldehyde unit and requires thiamine pyrophosphate (TPP) and Mg2+. This reversible non-oxidative reaction forms a three-carbon and a seven-carbon sugar phosphate.
Xylulose-5-phosphate + erythrose-4-phosphate → glyceraldehyde-3-phosphate + fructose-6-phosphate
Converts Xylulose-5-phosphate Erythrose-4-phosphate into Glyceraldehyde-3-phosphate Fructose-6-phosphate
› Notes
A second transketolase reaction, again requiring TPP and Mg2+, transfers two carbons to form another fructose-6-phosphate and glyceraldehyde-3-phosphate. The reversible non-oxidative phase therefore converts three pentose phosphates into two fructose-6-phosphate and one glyceraldehyde-3-phosphate.
Showing all 2 reactions.
What accelerates and inhibits it
Regulation is pathway-specific, so each context is listed separately
Pentose Phosphate Pathway (Oxidative and Non-oxidative phases)
Substrate availability; adequate TPP
Thiamine deficiency limits activity
No major acute direct hormonal control; flux follows pentose and glycolytic-intermediate demand
Recent literature
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