β-Lactoglobulin tryptic digestion: A model approach for peptide release

β-lg tryptic digestion leads to the release of a broad range of biologically active peptides. Understanding how these peptides are formed and the dynamics of the hydrolysis is of major relevance in order to control the quality of the final products. In this paper, the time-dependent release of peptides is reported and the dynamics of this release is discussed in terms of the physical accessibility of the enzyme to the scissile bonds and the secondary specificity of trypsin. In view of experimental data, a kinetic model based on first-order equations is proposed to simulate both β-lg degradation and peptide formation. The statistical data obtained seem to support the hypothesis that the hydrolysis mainly takes place via the proposed model. The results evaluated in this paper show the existence of areas within the intact protein with different susceptibility to tryptic attack. Whereas C- and N-terminal areas are easily digested, the internal part of the protein shows more resistance to hydrolysis and the release of final peptides within this region passes through the formation and subsequent degradation of intermediate peptides.

► The time-dependent release of peptides from tryptic digestion of β-lg is studied. ► Physical accessibility to scissile bonds: responsible of trypsin-resistance areas. ► Secondary specificity of the enzyme determines the dynamics of peptide release. ► Best fitting results for β-lg degradation and peptide release: first-order kinetics.