Noncompetitive tight-binding inhibition of Anticarsia gemmatalis trypsins by Adenanthera pavonina protease inhibitor affects larvae survival.

Abstract

The economic loss in soybean crops caused by the Lepidoptera insects has encouraged the search for new strategies to control this pest, which are currently based on synthetic insecticides. This paper evaluated the ability of ApTI (Adenanthera pavonina trypsin inhibitor) to inhibit trypsin-like proteins from Anticarsia gemmatalis by docking, molecular dynamics, and enzymatic and survival assay. The docking and molecular dynamic simulation between trypsin and ApTI were performed using the program CLUSPRO and NAMD, respectively. The inhibitory constant Ki and the inhibition type were determined through chromogenic assays. The survival assay of neonatal larvae under treatment with artificial diet supplemented with ApTI was also performed. The ApTI binding site was predicted to block substrate access to trypsin due to four interactions with the enzyme, producing a complex with a surface area of 1,183.7 Å2 . The kinetic analysis revealed a noncompetitive tight-binding mechanism. The survival curves obtained using Kaplan-Meier estimators indicated that the highest larvae mortality was 60%, using 1.2 mg of ApTI per 100 ml of artificial diet. The in vitro, in vivo, and in silico studies demonstrated that ApTI is a strong noncompetitive inhibitor of trypsin with biotechnological potential for the control of A. gemmatalis insect.