This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gluconeogenesis, Subject name: Biochemistry
[{'content': 'Which of the following is the major anaplerotic enzyme? \nSelect and explain. \nA. Pyruvate carboxylase, B. Acetyl-CoA carboxylase, C. Pyruvate dehydrogenase, D. Succinate dehydrogenase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. a)Pyruvate carboxylase Anaplerotic (gap-filling) reactions are the reactions that replenish the depleted TCA cycle intermediates that were used up in the biosynthetic reactions. Oxaloacetate is the catalyst of TCA cycle. Thus, production of oxaloacetate is the major anaplerotic reaction. Intermediate Depleted (used) by Replenished by Oxaloacetate Amino Acid synthesis Pyruvate carboxylase - Major anaplerotic enzyme Succinyl-CoA Heme Synthesis From Propionyl-CoA by carboxylase and Methyl malonyl-CoA mutase Oxaloacetate, Fumarate Gluconeogenesis From Amino acids', 'role': 'assistant'}]