This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
[{'content': 'Creatinine is synthesized from \nSelect and explain. \nA. Glycine, Arginine and Methionine, B. Glycine and Methionine, C. Ornithine and Glycine, D. Thymine and Ornithine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Creatine & CreatinineCreatinine is formed in muscle from creatine phosphate by irreversible, nonenzymatic dehydration, and loss of phosphate. Since the 24-hour urinary excretion of creatinine is propoionate to muscle mass, it provides a measure of whether a complete 24-hour urine specimen has been collected. Glycine, arginine, and methionine all paicipate in creatine biosynthesis. Synthesis of creatine is completed by methylation of guanidinoacetate by S-adenosylmethionine.Ref: Harper&;s Biochemistry; 30th edition; Chapter 30; Conversion of Amino Acids to Specialized Products', 'role': 'assistant'}]