This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
[{'content': 'Vitamin B12 acts as co-enzyme to which one of the following enzymes? \nSelect and explain. \nA. Isocitrate dehydrogenase, B. Homocysteine methyl transferase, C. Glycogen synthase, D. G-6-P dehydrogenase', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Vitamin B12 acts as co-enzyme to enzyme Homocysteine methyltransferase in the reaction <img src=" /> Folic acid deficiency may cause increased homocysteine levels in the blood. Plasma homocysteine levels above 15 micromoles / L is known to increase the risk of coronary aery diseases. Providing adequate doses of pyridoxine, B12, and folic acid may lower the homocysteine levels. Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 475, fig harper 44.14 page 558', 'role': 'assistant'}]