Scientist John Northrop is known for crystallizing many enzymes andproteins. One important enzyme he crystallized was chymotrypsin. In thefollowing years after his crystallization, other scientists contributed to thecharacterization of this enzyme, and now, it is one of the most well understoodproteases.Chymotrypsin is a digestive enzyme produced by the pancreas, and it isresponsible for the breakdown of proteins and polypeptides. Specifically, it isan endopeptidase, and breaks bonds within a polypeptide. Without chymotrypsin,proper food digestion cannot occur.
Chymotrypsin consists of two chains, and ismade up of 245 amino acids (Figure 1). The catalytic triad is animportant component of chymotrypsin. This triad consists of residues Serine 195,Histidine 57, and Aspartate 102 (Figure 2). Together, they work to stabilizethe enzyme and promote catalysis.
The aspartate and histidine are bound to eachother by hydrogen bonds, allowing histidine to work as a base for serine.Serine can then become a nucleophile to catalyze the breakdown of proteins.