Characterization of digestive α- and β-glucosidases in the midgut of Plagiodera versicolora Laicharting (Coleoptera: Chrysomelidae)

Abstract

The imported willow leaf beetle, Plagiodera versicolora is one of the main pests of forest trees worldwide including Iran. Activities of α- and β-glucosidases in the midgut of P. versicolora adults were studied in this research. The results showed a higher α- glucosidase activity of adultsthan β-glucosidase. The optimal pHs for α- and β-glucosidases activities were found to be 6 and 9, respectively. Optimal temperatures for the enzymatic activities were recorded at 30 and 25 °C, respectively. Concentration of 0.5 mM K+ significantly minimized the activity of α- glucosidase and maximized the activity of α-glucosidase in presence of Ca2+. The activity of β-glucosidase was decreased by adding Mg2+ and Zn2+. 5 mM concentration of K+ had the most inhibitory impact on β-glucosidase activity, while 0.5 mM concentration of Na+ showed the most positive effect on the enzyme activity. The Km of midgut α- and β- glucosidase was 0.36 and 2.03 mM and the Vmax value was 5.46 and 18.51 μmol/min/mg protein, respectively.

Keywords

• plagiodera versicolora
• α-glucosidase
• β-glucosidase
• iran
• midgut