Identification and molecular mechanisms of DPP-IV inhibitory peptides from fish maw collagen hydrolysates: An integrated approach combining targeted enzymatic hydrolysis, peptidomics, molecular dynamics, and network pharmacology

Collagen-rich aquatic materials are promising sources of food-derived bioactive peptides, yet the DPP-IV inhibitory potential of fish maw collagen remains insufficiently explored. In this study, fish maw collagen was hydrolyzed to prepare DPP-IV inhibitory peptides, and their peptide basis and potential inhibitory mechanisms were investigated. Among five commercial proteases, Novozymes 37071 was selected for its superior hydrolytic efficiency and DPP-IV inhibitory activity. A practical hydrolysis condition of 55 °C, 6 h, 2.0% enzyme dosage, and pH 9.0 was selected and verified, yielding a hydrolysate with 97.03% protein recovery, 20.68% degree of hydrolysis, and 66.62% DPP-IV inhibition. The optimized hydrolysate showed good pH and thermal stability, retained inhibitory activity during simulated gastrointestinal digestion, and exhibited concentration-dependent antioxidant activities. LC-MS/MS identified 927 peptides, mainly low-molecular-weight short peptides enriched in proline and hydrophobic residues. A stepwise in silico screening strategy based on abundance, predicted bioactivity, safety, solubility, and ADMET properties narrowed the peptide pool to 22 candidates. Molecular docking suggested that several peptides could interact with key DPP-IV recognition residues through hydrogen bonding and hydrophobic interactions. Among the synthesized peptides, GPA showed the strongest DPP-IV inhibitory activity, with an IC 50 value of 0.464 mg/mL, whereas PGAGF was the most active peptide selected through the virtual screening workflow, with an IC 50 value of 10.449 mg/mL. Kinetic analysis indicated reversible competitive inhibition, and molecular dynamics simulations supported stable PGAGF-DPP-IV and GPA-DPP-IV binding. Overall, fish maw collagen is a promising source of DPP-IV inhibitory peptides for glycemic regulation-oriented food applications.