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 beta-lactoglobulin (beta-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 beta-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. (C) 2011 Elsevier Ltd. All rights reserved.