Exploration of Dipeptidyl Peptidase-IV (DPP-IV) Inhibitory Peptides from Silkworm Pupae (<i>Bombyx mori</i>) Proteins Based on <i>In Silico</i> and <i>In Vitro</i> Assessments

Abstract

This study aimed at exploring dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides from silkworm pupae proteins by <i>in silico</i> analysis and <i>in vitro</i> assessments. <i>In silico</i> analysis of 274 silkworm pupae proteomes indicated that DPP-IV inhibitory peptides can be released from silkworm pupae proteins. <i>In vitro</i> assessments revealed that pepsin and bromelain led to better production of DPP-IV inhibitory peptides from silkworm pupae protein. Notably, peptide fractions (<1 kDa) from pepsin- and bromelain-treated hydrolysates exhibited more potent DPP-IV inhibitory activities. Two novel DPP-IV inhibitory peptides (Leu-Pro-Pro-Glu-His-Asp-Trp-Arg and Leu-Pro-Ala-Val-Thr-Ile-Arg) were identified by LC-MS/MS with IC₅₀ values of 261.17 and 192.47 μM, respectively. Enzyme kinetics data demonstrated that these two peptides displayed a mixed-type DPP-IV inhibition mode, which was further validated by molecular docking data. Overall, <i>in silico</i> analysis combined with <i>in vitro</i> assessments can serve as an effective and rapid approach for discovery of DPP-IV peptides from silkworm pupae proteins.