Vitamin B1 (Thiamine) Biochemistry
Summary
Thiamine (Vitamin B1) is a water-soluble vitamin and an important constituent of TPP (thiamine pyrophosphate), a cofactor found in several important dehydrogenase reactions. Specifically, TPP is an important cofactor for pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and branched-chain ketoacid dehydrogenase. Besides dehydrogenase reactions, TPP also serves an important role as a cofactor for transketolase.
Key Points
- Vitamin B1 (Thiamine)
- Active form is thiamine pyrophosphate (TPP), a cofactor for several dehydrogenases and other enzymes:
- Pyruvate dehydrogenase
- Links glycolysis to TCA cycle (see Pyruvate Metabolism), enabling cells to metabolize glucose to produce energy
- Deficiency leads to necrosis of some glucose-dependent tissues (esp. mamillary body in brain), such as seen in Thiamine Deficiency
- α-ketoglutarate dehydrogenase
- Enzyme in the TCA cycle
- Transketolase
- Important in Hexose Monophosphate (HMP) Shunt
- Erythrocyte (RBC) transketolase activity decreased in deficiency
- Branched-chain ketoacid dehydrogenase
- Thiamine supplementation useful in Maple Syrup Urine Disease (MSUD), caused by deficiency of above
- Pyruvate dehydrogenase
- Active form is thiamine pyrophosphate (TPP), a cofactor for several dehydrogenases and other enzymes:
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