Peptides Derived From Reactive Center Loops Inhibit Digestive Trypsin-Like Enzymes in Lepidopteran Pests

Soybean yield is often reduced by pest attacks. Among these, Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) stands out as one of the most important defoliating pests of soybean. Therefore, the development of new bioinsecticides targeting Lepidopteran pests is an urgent need. Protease inhibitors (PIs) have emerged as promising molecules in this context. In this study, we designed four peptides (TGPCK, TGPCR, AVIMK, and AVIMR) inspired by the reactive center loops of BPTI and SKTI to assess their potential as competitive inhibitors of trypsin-like proteases in A. gemmatalis. In silico and kinetic analyses revealed that peptide binding affinity was influenced by specific chemical interactions, with pi-sigma bonds correlating with higher affinity for AVIMK, while alkyl/pi-alkyl and C-H bonds were associated with lower affinity for AVIMR and TGPCK. Key residues (His57, Asp102, Ser195, Asp189, S195, and G197) played a crucial role in ligand binding. Enzyme inhibition assays confirmed that all peptides acted as competitive inhibitors of A. gemmatalis trypsin-glen proteases, with TGPCK displaying the highest efficacy. These findings highlight BPTI-derived peptides as potential candidates for future pest management strategies. Further studies should evaluate their effects when applied to plants, considering possible metabolic interactions and phytotoxicity.