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