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': 'Amino acid which acts as a buffer at the physiological pH of 7.4 is: \nSelect and explain. \nA. Glycine, B. Histidine, C. Lysine, D. Arginine', 'role': 'user'}, {'content': "Answer: B \nExplanation: The pK value of imidazolium group of Histidine is 6.1 and therefore effective as a buffer at the physiological pH of 7.4. The buffering capacity of plasma proteins and hemoglobin is mainly due to histidine residue. Also Know: Pauly's test is used to detect the amino acid group Imidazole (Histidine.) Ref: Textbook of Biochemistry By DM Vasudevan 5th Ed Page 20, 22", 'role': 'assistant'}]