RESUMO
The Indianmeal moth, Plodia interpunctella, is one of the most damaging pests of stored products. We investigated the insecticidal properties of ApKTI, a Kunitz trypsin inhibitor from Adenanthera pavonina seeds, against P. interpunctella larvae through bioassays with artificial diet. ApKTI-fed larvae showed reduction of up to 88% on larval weight and 75% in survival. Trypsin enzymes extracted from P. interpunctella larvae were inhibited by ApKTI, which also demonstrated capacity to bind to chitin. Kinetic studies revealed a non-competitive inhibition mechanism of ApKTI for trypsin, which were further corroborated by molecular docking studies. Furthermore, we have demonstrated that ApKTI exhibits a hydrophobic pocket near the reactive site loop probably involved in chitin interactions. Taken together, these data suggested that the insecticidal activity of ApKTI for P. interpunctella larvae involves a dual and promiscuous mechanisms biding to two completely different targets. Both processes might impair the P. interpunctella larval digestive process, leading to larvae death before reaching the pupal stage. Further studies are encouraged using ApKTI as a biotechnological tool to control insect pests in field conditions.
Assuntos
Fabaceae/química , Inseticidas/química , Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Inibidores da Tripsina/química , Inibidores da Tripsina/farmacologia , Animais , Biomassa , Quitina , Inseticidas/isolamento & purificação , Larva , Modelos Moleculares , Conformação Proteica , Sementes/química , Relação Estrutura-Atividade , Tripsina/química , Inibidores da Tripsina/isolamento & purificaçãoRESUMO
A salt-tolerant cellulase secreted by a marine Bacillus sp. SR22 strain with wide resistance to temperature and pH was purified and characterized. Its approximate mass was 37 kDa. The endoglucanase, named as Bc22Cel, was purified by ammonium sulfate precipitation, gel filtration chromatography, and extraction from the gel after non-reducing sodium dodecyl sufate-polyacrylamide gel electrophoresis. The optimal pH value and temperature of Bc22Cel were 6.5 and 60°C, respectively. The purified Bc22Cel showed a considerable halophilic property, being able to maintain more than 70% of residual activity even when pre-incubated with 1.5 M NaCl for 1 h. Kinetic analysis of the purified enzyme showed the Km and Vmax to be 0.704 mg/ml and 29.85 µmol·ml-1·min-1, respectively. Taken together, the present data indicate Bc22Cel as a potential and useful candidate for industrial applications, such as the bioconversion of sugarcane bagasse to its derivatives.