Kinetic modeling of demasking and hydrolysis of peptide bonds during proteolysis of β-lactoglobulin by trypsin.

Proteolysis of β-lactoglobulin by trypsin was studied with fluorescence spectroscopy and an empirical exponential model was engaged to describe the peptide bond hydrolysis kinetics. The shift in the fluorescence maximum of tryptophan residues, from 342 to 352 nm, in the course of β-lactoglobulin degradation was used as an indicator of the transition of masked peptide bonds to the demasked ones, which were accessible for the enzyme action. A simple equation with only two parameters was suggested to link together the degree of demasking of peptide bonds and the degree of their hydrolysis, allowing the kinetic description of proteolysis.