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': 'Active sites of serine protease contain \nSelect and explain. \nA. Histidine, B. Lysine or threonine, C. Arginine, D. Serine', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Serine proteases name stems from the nucleophilic Ser (serine) in the enzyme active site Nucleophilicity of the catalytic Ser is typically dependent on a catalytic triad of Asp, His, and Ser residues, commonly referred to as the charge relay system Ref: biochemistry by U. Satyanarayana 3rd edition Pgno : 171', 'role': 'assistant'}]