Which amino acid acts as a general acid and a general base in the mechanism of chymotrypsin?

Question

Quizplus · Accepted Answer

His57 acts as a general acid by donating a proton to the oxygen on the carbonyl group of the substrate, and as a general base by accepting a proton from the serine hydroxyl group during the formation of the acyl-enzyme intermediate. Ser195 acts as a nucleophile and attacks the carbonyl carbon of the substrate, while Gly193 and Asp102 facilitate the stabilization of the transition states during the hydrolysis of the peptide bond.

Which Amino Acid Acts as a General Acid and a General