This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'NO is synthesized by all except - \nSelect and explain. \nA. Endothelium, B. Neuron, C. Macrophages, D. Platelets', 'role': 'user'}, {'content': "Answer: D \nExplanation: Platelets\no Three isoforms of NO synthase have been identified Neuronal NOS (nNOS or NOS-1); (ii) Macrophage or inducible NOS (iNOS orNOS-2); and (Hi) Endothelial NOS (eNOS or NOS-3). NOS-1 and NOS-3 are constitutive enzymes, whereas NOS2 is inducible in inflammatory' conditions.\no NOS-1 and NOS-3 are activated by Ca +2Q\no NO synthase is a very complex enzyme, employing five redox cofactors: NADPH, FAD, FMN, heme, and tetrahydrobiopterin Q .", 'role': 'assistant'}]