Release pattern of potent dipeptidyl peptidase IV(DPP-IV) inhibitory peptides from tilapia (Oreochromis niloticus) skin collagen.

Gly-Pro-type peptides consisting of 4-9 amino acids are the most potent DPP-IV inhibitory peptides in collagen. In this study, we investigated the release patterns of collagen-derived Gly-Pro-type peptides with DPP-IV inhibitory activities by analyzing the cleavage selectivity of proteases, and the dynamic release mechanism of Gly-Pro-type peptides. Results showed that collagen hydrolysate with the highest DPP-IV inhibitory activity was obtained by proteaC (IC = 0.58 ± 0.02 mg/mL). Large amounts of Gly-Pro-type peptides consisting of 4, 6, and 9 amino acids were released. ProteaC preferred to cleave Gly and hydrophobic amino acids residues at the P1' position, and had a strong cleavage preference for Hyp residue at the P1 position. The dynamic release mode indicated that the release of potent DPP-IV inhibitory peptides underwent a change from precursor peptides to target peptides and then to short peptides. These findings provided a better understanding of the release of DPP-IV inhibitory peptides.