Thiamine is not used in which of the following reactions
Lactate to pyruvate
Alphaketoglutarate to succinyl CoA
Glucose to pentose
Oxidative decarboxylation of alpha keto amino acids.
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.
Vitamins