Thiamine deficiency causes lactic acidosis due to defect in the action of?

Ans. d (Pyruvate dehydrogenase). (Ref. Harper, Biochemistry, 25th ed., 197)Inhibition of pyruvate metabolism leads to lactic acidosis.# Arsenite, mercuric ions, dietary deficiency of thiamine, inhibits pyruvate dehydrogenase, and allows pyruvate to accumulate.# Thiamine is a cofactor for several enzymes like- Transketolase,- Pyruvate dehydrogenase and- a-KG dehydrogenase.# If nutritionally deprived alcoholics are given glucose, thiamine deficiency causes rapid accumulation of pyruvate and lactic acidosis. Patient with inherited pyruvate dehydrogenase deficiency have same features particularly after glucose load.#IV thiamine is treatment of choice in Wernicke's encephalopathy.QINHIBITORS OF METABOLIC PATHWAYS EnzymeInhibitorPathway1.AconitaseFluoroacetateKreb's cycle2.L-KG dehydrogenaseArseniteKreb's cycle3.EnolaseFluorideGlycolysis4.Succinate dehydrogenaseMalonate oxaloacetateKreb's cycle5,Giyceradehyde-3 phosphatelodoacetate dehydrogenaseGlycolysis6.MOAIproniazid 7.Pyruvate dehydrogenaseArsenite 8.Carbonic anhydraseSulfanilamide