This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Glycine Metabolism Detail, Subject name: Biochemistry
[{'content': 'Glycine can be synthesized by all except: \nSelect and explain. \nA. Glyoxalate, B. Leucine, C. Serine, D. Threonine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Glycine metabolism The pink boxes (serine, threonine, and glyoxylate)are the one from which glycine can be formed Substrate Enzyme catalysing Threonine Threonine aldolase Serine serine-hydroxy methyl transferase Glyoxylate glycine transaminase Extra information: Glycine can also be synthesized from choline through betaine and sarcosine as intermediates in the pathway.', 'role': 'assistant'}]