Medicine & USMLE

Vitamin B1 (Thiamine) Biochemistry

  1. Vitamin B1 (Thiamine) Biochemistry
  2. Vitamin B1 (Thiamine) Deficiency
  3. Vitamin B2 (Riboflavin)
  4. Vitamin B3 (Niacin) Biochemistry
  5. Vitamin B3 (Niacin) Deficiency and Excess
  6. Hartnup Disease
  7. Vitamin B5 (Pantothenic Acid)
  8. Vitamin B6 (Pyridoxine)
  9. Vitamin B7 (Biotin)
  10. Vitamin B9 (Folate)
  11. Vitamin B12 (Cobalamin) Biochemistry
  12. Vitamins B9 and B12 Deficiencies
  13. Vitamin A (Retinol) Biochemistry
  14. Vitamin A (Retinol) Deficiency and Excess
  15. Vitamin C (Ascorbic Acid) Biochemistry
  16. Vitamin C (Ascorbic Acid) Deficiency and Excess
  17. Vitamin D Biochemistry
  18. Vitamin D Deficiency and Excess
  19. Vitamin E (Tocopherol/Tocotrienol)
  20. Vitamin K Biochemistry
  21. Vitamin K Deficiency
  22. Zinc
  23. Kwashiorkor and Marasmus


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
      • Branched-chain ketoacid dehydrogenase

Find Thiamine Biochemistry and other Vitamins among Pixorize's visual mnemonics for the USMLE Step 1 and NBME shelf exams.