Comparison of goat and sheep β-lactoglobulin to bovine β-lactoglobulin as potential source of dipeptidyl peptidase IV (DPP-4) inhibitors

We recently reported on the presence of DPP-4 inhibitors among bioactive peptides generated by proteolysis of β-lactoglobulin (β-LG), proving that the bioactive peptide Ile-Pro-Ala (IPA) can be regarded as a moderate DPP-4 inhibitor and could be a molecular determinant of the previously observed inhibitory effect of whey protein ingestion on DPP-4 activity in the proximal bowel of mice. The aim of the present study was to predict differences in potential DPP-4 inhibitory activity between goat/sheep and bovine β-LG hydrolysates by means of in silico analysis and in vitro DPP-4 activity assay. Combined results proved that caprine/ovine whey is richer in the content of short amino acid sequences carrying weak DPP-4 inhibitory activity than bovine whey. Based on in vitro analysis, no significant differences should be expected in activity between species due to the leading role of the conserved IPA peptide.