Electrostatic effect of trypsin binding on the hydrogen exchange rate of bovine pancreatic trypsin inhibitor beta-sheet NH's

The changes of H-D exchange rates upon protein-protein interactions are generally interpreted as a result of the changes of the dynamic properties of the proteins. The effect of trypsin binding on the H-D exchange kinetics of some trypsin inhibitor amide H's was reported (Simon et al., 1984). In this paper the electrostatic potential originating from the trypsin molecule is calculated at the positions of the studied amide H's in the trypsin-trypsin inhibitor complex. We conclude that the observed decrease of the exchange rates is mainly due to the electrostatic field of the trypsin molecule.