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In silico exploration of inhibition potency of maslinic acid, a plant based triterpene, against Helicoverpa armigera serine protease

Ware, Akshay P., Shaikh, Faiyaz K., Panche, Archana N., Harke, Sanjay N.
Journal of Asia-Pacific entomology 2019 v.22 no.1 pp. 33-40
Helianthus annuus, Helicoverpa armigera, active sites, amino acids, binding capacity, cattle, crops, databases, insect pests, models, triterpenoids, trypsin, zinc
Gut proteases are accountable for survival of Helicoverpa armigera on protein rich parts of plant devastating many important agricultural crops. The aim of present study was to identify potential natural compounds having inhibitory potency against Helicoverpa armigera gut proteases. We have modeled structure of H. armigera serine protease (UniProt ID: O18447) and analyzed its interactions with maslinic acid (Zinc ID: ZINC38140521). A 3D model was generated using bovine trypsin in complex with analogues of sunflower inhibitor 1 as template with the help of Chimera Modeler 1.11. The PROCHECK and Modfold analysis have revealed 81.8% of residue in favored region. The POOL and COACH analysis have revealed 18 amino acids in the active site. In the 10 ns MD simulations of modeled structure, the RMSD of the protein backbone increased slightly and later stabilized from 7 ns to 10 ns. The modeled structure was stabilized at gyration distance of about 1.65 nm at 7 ns. Potential hit compounds from the ZINC database identified in this study showed good inhibitory bindings with modeled structure. Among these compounds maslinic acid, a plant based pentacyclic triterpenes was found to be potent lead compound with good binding affinity (−9.5 kcal/mol). RMSD profile was <0.45 nm for complex with stabilization at about 18,000 ps (18 nm) suggesting stable interaction. This work demonstrates reasonable in silico inhibitory action of maslinic acid against H. armigera serine protease and depicts utility of in silico methodologies for designing competent strategies against dreaded insect pests like H. armigera.