A proteomics approach to characterizing limited hydrolysis of whey protein concentrate

Whey Protein Concentrate was hydrolyzed by trypsin and Protease M, a novel endo/exopeptidase mix from Aspergillus oryzae. Protein peptide profiling demonstrated that Protease M preferentially hydrolyzed α-lactalbumin (α-la), while trypsin targeted β-lactoglobulin (β-lg). Peptide fractions were analyzed by liquid chromatography coupled with tandem mass-spectrometry to characterize differences in enzyme specificity, peptide hydrophobicity, and bioactivity, using bioinformatics tools. While trypsin cleaved at the C-terminal end of lysine and arginine, Protease M contributed to pepsin-like endopeptidase activity coupled with carboxyl, amino, and leucine exopeptidase activity, resulting in relatively more hydrophilic peptides compared to those released by trypsin hydrolysis. While trypsin and Protease M had varying specificity, 9 bioactive peptides were common among the hydrolysates, which was attributed to the exopeptidase activity of Protease M. The proteomics coupled with bioinformatics approach provided fundamental knowledge needed to optimize whey protein hydrolysis in a direct and efficient manner for targeted applications.