This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzymes, Subject name: Biochemistry
[{'content': 'Major mono-oxygenase in the endoplasmic reticulum is: \nSelect and explain. \nA. Cytochrome P450, B. Cytochromes, C. Epoxide reductase, D. Glutathione reductase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. Cytochrome P450Cytochrome P450 is the major monooxygenase present in the endoplasmic reticulum. The usage 450 refers to the absorption peak exhibited by the enzymes when exposed to carbon monoxide.Most of the reactions involve the addition of a hydroxyl group to aliphatic or aromatic compounds.', 'role': 'assistant'}]