Thiamine is not used in which of the following reactions

Ans. is 'a' i.e., lactate to pyruvate :Lactate to pyruvate or pyruvate to lactate is a reversible reaction that is catalysed by the enzyme lactate dehydrogenase. Coenzyme is Niacin or vit. B3Thiamine is used as a coenzyme in mainly two types of reactionTransketolase reaction (in HMP shunt)2) Oxidative decarboxylation of alpha-keto acids (eg. Pyruvate and alpha-ketoglutarate)Pyruvate (Pyruvate dehydrogenase complex)- Acetyl CoA Alpha ketoglutarate -(Alpha ketoglutarate dehydrogenase complex -Suddenly CoAAlso remember the following :Coenzymes required for the following reactions:*Transamination reactions-B6 (Pyridoxine as pyridoxal phosphate)*Deamination reactions- B6 Fatty acid oxidation-B2 (Riboflavin)*Propionyl Co A to Methyl malonyl Co A- Biotin*Pyruvate to oxaloacetate- Biotin*Acetyl Co A to Malonyl Co A- Biotin*Pyruvate dehydrogenase complex- Thiamine*,- B, (Riboflavin) *- Niacin *- Lipoic acid*Alpha-ketoglutarate dehydrogenase complex- Thiamine(B )*- (ie alpha-ketoglutarate to succinyl Co A) - Riboflavin (B2)*- Niacin*- Lipoic acid*Succinate dehydrogenase (ie. Succinate to fumarate) - Riboflavin(B2)*Note: that this topic of vitamins as coenzymes is very important. A look at figure on page no. 320 of Lippincott, 2/e would definitely help you.