Our long term goal is to design a protease with restriction enzyme-like specificity. R.J. Structural Origins of Substrate Discrimination in Trypsin and Chymotrypsin. The importance of the interplay between protein conformation, dynamics and electrostatics in enzyme catalysis is undeniable on an intellectual level. However, the concrete demonstration of the relationship between these phenomena has proven experimentally elusive. We are approaching this problem by studying the conformational change which occurs during the biosynthesis of trypsin.
Trypsin is synthesized as an inactive precursor, trypsinogen.
This zymogen is activated by removal of a peptide from the N-terminus. The new N-terminus, Ile16, forms a salt bridge with Asp194. This interaction triggers a conformational change involving four disordered segments of trypsinogen. These segments form the rigid S1 substrate binding site and oxyanion hole. Thus the conformational change is essentially an example of protein folding, albeit on a smaller and more confined scale.