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': 'At pH 7 the binding of 2,3-BPG to hemoglobin occurs at which site? \nSelect and explain. \nA. Sulphydryl group, B. Carboxy terminal, C. Amino terminal, D. Histidine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: 2,3-BPG Stabilizes the T Structure of HemoglobinA low Po2 in peripheral tissues promotes the synthesis of 2,3-bisphosphoglycerate (BPG) in erythrocytes. The hemoglobin tetramer binds one molecule of BPG in the central cavity formed by its four subunits (Figure 6-6). However, the space between the H helices of the b chains lining the cavity is sufficiently wide to accommodate BPG only when hemoglobin is in the T state. BPG forms salt bridges with the terminal amino groups of both b chains Val NA1 and with Lys EF6 and His H21.Ref: Harper&;s Biochemistry; 30th edition; Chapter 6 Proteins: Myoglobin & Hemoglobin', 'role': 'assistant'}]