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': 'Glycine can be synthesized from all, EXCEPT: \nSelect and explain. \nA. Choline, B. Serine, C. Alanine, D. None of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Glycine aminotransferases can catalyze the synthesis of glycine from glyoxylate and glutamate or alanine. Unlike most aminotransferase reactions, these strongly or glycine synthesis. Additional impoant mammalian routes for glycine formation are from choline and from serine Ref: Harper 28th edition, chapter 27.', 'role': 'assistant'}]