Biochemistry: Important Physiological role and Deficiency manifestations of Thiamine

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Physiological Role of Thiamine

  • The biologically active form of Thiamine is known as Thiamine pyrophosphate or TPP.
  • It acts as a Coenzyme in the following reactions:
1. Pyruvate dehydrogenase
  • Thiamine pyrophosphate (TPP) is used in oxidative decarboxylation of alpha keto acids, e.g. pyruvate dehydrogenase catalyzes the breakdown of Pyruvate, to Acetyl CoA, and carbon dioxide.
2. Alpha ketoglutarate dehydrogenase
  • Another similar biochemical reaction that requires TPP is the Oxidative decarboxylation of alpha ketoglutarate to succinyl CoA and CO2 in Citric acid cycle.
3. Transketolase
  • The second group of enzymes that use TPP as co-enzyme are the transketolases in the Hexose monophosphate shunt pathway (HMP) of glucose.
  • The main role of Thiamine pyrophosphate (TPP) is in carbohydrate metabolism.
  • So, the requirement of Thiamine is increased along with higher intake of carbohydrates.

Deficiency Manifestations of Thiamine

  • The oxidative decarboxylation of Pyruvate and alpha ketoglutarate play a major role in energy metabolism of most of the cells especially in the tissues of the nervous system.
  • In Thiamine deficiency, the activity reactions that are catalyzed by the two dehydrogenases is decreased.
  • This results in the decreased production of ATP and impaired cellular function.
  • The deficiency of Thiamine may be manifested as a disease called as Beriberi.


  •  Beriberi  is a severe Thiamine deficiency syndrome found among Asians where rice is a staple food, especially if eating well-polished rice where Thiamine has been removed.
  • Early symptoms are anorexia, dyspepsia, heaviness and weakness.
  • The early symptoms are anorexia, dyspepsia, heaviness and weakness.
  • Subjects feel weak and get easily exhausted.
  • Different types are:
  • Wet Beriberi
  • Dry Beriberi
  • Infantile Beriberi
  • Wernicke-Korsakoff Syndrome


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