Application of a Combined Peptidomics and Approach for the Identification of Novel Dipeptidyl Peptidase-IV-Inhibitory Peptides in Digested Pinto Bean Protein Extract.

The conventional approach in bioactive peptides discovery, which includes extensive bioassay-guided fractionation and purification processes, is tedious, time-consuming and not always successful. The recently developed bioinformatics-driven approach is rapid and cost-effective; however, it lacks an actual physiological significance. In this study a new integrated peptidomics and method, which combines the advantages of the conventional and approaches by using the pool of peptides identified in a food hydrolysate as the starting point for subsequent application of selected bioinformatics tools, has been developed. Pinto bean protein extract was digested and peptides were identified by peptidomics. The pool of obtained peptides was screened by analysis and structure-activity relationship modelling. Three peptides (SIPR, SAPI and FVPH) were selected as potential inhibitors of the dipeptidyl-peptidase-IV (DPP-IV) enzyme by this integrated approach. In vitro bioactivity assay showed that all three peptides were able to inhibit DPP-IV with the tetra-peptide SAPI showing the highest activity (IC50 = 57.7 μmol/L). Indeed, a new possible characteristic of peptides (i.e., the presence of an S residue at the N-terminus) able to inhibit DPP-IV was proposed.