This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: TCA Cycle, Subject name: Biochemistry
[{'content': 'Rate limiting step of TCA : \nSelect and explain. \nA. Citrate synthase, B. Isocitrate dehydrogenase, C. Alpha-ketoglutarate dehydrogenase, D. All', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 3 enzymes which are rate limiting in TCA cycle Irreversible steps of TCA 1. Citrate Synthase 1. Citrate Synthase (preferred) 2. Isocitrate Dehydrogenase 2. Alpha-Ketoglutarate Dehydrogenase. 3. Alpha-Ketoglutarate Dehydrogenase', 'role': 'assistant'}]