This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: miscellaneous, Subject name: Biochemistry
[{'content': 'Nitric Oxide Synthase \nSelect and explain. \nA. Is inhibited by Ca++, B. Catalyzes a dioxygenase reaction, C. Accepts electrons from NADH, D. Requires NADH, FAD, FMN & Heme iron', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Nitric oxide is formed from arginine by the enzyme nitric-oxide synthase (NOS).It contains heme, FAD, FMN and tetrahydrobiopterin. The enzyme utilizes NADPH and molecular oxygen. Calmodulin is required to modulate its activity.The guanidino nitrogen of arginine is incorporated into NO.. From the molecular oxygen, one atom is added to NO. and the other into citrulline. Therefore, the enzyme is a di-oxygenase Ref: D M Vasudevan 7th edition Page no: 228', 'role': 'assistant'}]