Electronic aspects of serine protease catalysis.

A new electrostatic approach is applied to serine protease catalysis. It is is based upon the demonstration that the polarities, or partial charges, of the atomic components of the molecules involved in the reaction alternate in sign. When the atomic components of opposite polarities of the enzyme and substrate approach close to each other during the catalysis, the electrostatic interactions between them increase in intensity. These increasing interactions are related to the decrease in the energy barrier. When the serine protease--catalyzed reaction is followed from this perspective, it is shown to result in a marked simplification of the catalytic mechanism. A number of concerted proton transfers and electron density displacements around the active site are indicated. This approach is not inconsistent with other electrostatic methods, and is supported by independent partial charge calculations.