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: Pharmacology
[{'content': 'Metabolism of drugs is mostly done by which enzyme \nSelect and explain. \nA. Cytochrome C, B. Cytochrome P450, C. Glucuronyl transferase, D. Acetylase', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Biotransformation reactions (metabolism) of drugs can be classified :\n\nA. Non-synthetic (phase I) reactions\n\n\xa0Metabolism brings about a change in the drug molecule by:\n\n1. Oxidation\xa0\n2. Reduction\n3. Hydrolysis\n4. Cyclization\n5. Decyclization\n\n\xa0The new metabolite may retain biological activity or it may be an inactive metabolite.\n\xa0Oxidation is the most important metabolizing reaction.\n\xa0The most important enzyme for oxidation reaction is cytochrome P450\n\nB. Synthetic (phase II or conjugation) reaction\n\n\xa0Metabolism involves the union of the drug with one of several polar (water-soluble) endogenous molecules that are products of intermediary metabolism, to form a water-soluble conjugate which is readily eliminated by kidney or, if the molecular weight exceeds 300, in the bile.\n\xa0Phase II metabolism almost invariably terminates biological activity, i.e. metabolites are usually inactive.\n\xa0Reactions are:-\n\n1. Acetylation\n2. Glucuronide conjugation\n3. Glycine conjugation\n4. Glutathione conjugation\n5. Sulfate conjugation\n6. Methylation\n7. Nucleotide synthesis', 'role': 'assistant'}]