This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzyme basics and serine proteases, Subject name: Biochemistry
Histidine is present at the catalytic site of which of the following enzymes 
Select and explain. 
A. Hexokinase, B. Carboxypeptidase, C. Trypsin, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Active center of enzymes:- Name of enzyme Impoant amino acid at the catalytic site Chymotrypsin His(57), Asp(102), Ser(195) Trypsin Serine, Histidine Thrombin Serine,Histidine Phosphoglucomutase Serine Alkaline phosphatase Serine Carbonic anhydrase Cysteine Hexokinase Histidine Carboxypeptidase Histidine,Arginine,Tyrosine Aldolase Lysine