Question

The low barrier hydrogen bond formed between the buried Asp 102 and His 57 residues of the catalytic triad in the chymotrypsin mechanism serves to

Answer 1

Chymotrypsin is an digestive enzyme which functions to degrade and digest the proteins. It basically plays a critical role in proteolysis. This enzyme is located in the pancreas. The enzyme comprises of a catalytic triad which consist of three amino acids which work in conjunction with each other. The three amino acids present in the catalytic triad are Serine 195, Histidine 57 and Aspartate 102. Chymotrypsin is a serine protease by nature and it undergoes a nucleophilic reaction to cause proteolysis. But the Serine 195 contains a alcohol group as a side chain and alcohol group does not function as a good nucleophile. Due to this characteristic it is crucial for converting the alcohol group to some other group which works as a good nucleophile. Therefore, the target is to convert alcohol group to alkoxide group. The Aspartate 102 and the Histidine 57 have a low barrier hydrogen bond within themselves. This makes the Histide side chain change its orientation which allows the Serine to function in the desired way. Therefore the low barrier hydrogen bond formed between the buried Asp 102 and His 57 residues of the catalytic triad work to change the alcohol group of Ser 195 to alkoxide group which favours the protein degradation process.