Identification and characterization of dipeptidyl peptidase IV inhibitory peptides from wheat gluten proteins

The objective of this study was to investigate the dipeptidyl peptidase IV (DPP-IV) inhibitory properties of wheat gluten-derived peptides. Wheat gluten protein was hydrolyzed by flavourzyme, papain, neutral protease, and alkaline protease with or without subsequent hydrolysis by trypsin. Results showed that the wheat gluten hydrolysate by flavourzyme displayed the highest DPP-IV inhibitory activity with IC50 of 1.25 +/- 0.09 mg/mL. After purified by Sephadex G-15 gel column, the fraction F1 from the hydrolysate by flavourzyme had a superior DPP IV inhibitory activity with IC50 of 0.15 +/- 0.04 mg/mL. The peptide sequences from F1 were identified by UPLCMS/MS and found that six wheat gluten-derived peptides of LPF, MPF, MAMG, VAVPV, MAMGL, and LAGAP showed DPP-IV inhibitory activity. MPF and VAVPV exerted the highest DPP-IV inhibitory activity of 57.33% +/- 4.11% and 56.08% +/- 1.40% at the concentration of 500 mu M, respectively. In addition, molecular docking revealed that MPF and VAVPV were predicted to form multiple hydrogen bonds, attractive charge, and hydrophobic interactions with the residues located in the active site of DPP-IV, which might contribute to the DPP-IV inhibitory activity. It indicates that wheat gluten is a good source for DPP-IV inhibitory peptides, and wheat gluten-derived DPP-IV inhibitory peptides have potential as ingredients in functional foods or candidates of drugs for the management of prediabetes and Type 2 diabetes mellitus.