Biochemical characterization of digestive β-glucosidase from midgut of Leiptinotarsa decemlineata (Coleoptera: Chrysomelidae)

The Colorado potato beetle, Leptinotarsa decemlineata Say (Col.: Chrysomelidae) is an important pest of potato worldwide and study of its glucosidases is an important step to develop appropriate pest control strategies. In this study, some biochemical aspects of β-glucosidase in the Colorado potato beetle were determined. The results showed that β-glucosidase activity in the midgut of adults was 6.68 Umg^-1. Maximum activity of midgut β-glucosidase occurred at pH 4 to pH 5.5; however, the enzyme is active at pH 3 to pH 7 more than 50% of its relative activity. The enzyme was stable at pH 3 to pH 8 for 2 and 8 hours incubation time. According to the results, optimal temperature for the enzyme activity was 50 °C and its stability significantly was reduced at 50 °C during 1 to 8 days incubation time. The enzyme activity decreased with the addition of different concentrations of MgCl2, urea, Tris and CaCl2. Enzyme activity was highly decreased at low concentrations of SDS (1 mM).