Characterization of caboxyl esterases from american bollworm in Punjab

Location specific caboxyl esterases from Helicoverpa armigera (Lepidoptera: Noctuidae) in Punjab were examined for activity and were characterized by electrophoresis and biochemical methods. Optimum activities were observed with phosphate buffer (0.1 M 6.5) for caboxyl esterases of all three regions (Ludhiana, Hoshiarpur and Mansa) at 37°C. The Km values were 0.33, 0.50 and 1.0 mM from Ludhiana, Mansa and Hoshiarpur regions, respectively. Diurnal effect showed maximal activity at 09.00am (13.43 ± 2.08 μg of α-napthol formed/g of American bollworm/min) and crop wise effect on caboxyl esterases showed maximal activity in larvae fed on cotton leaves (451.85 ± 78.79). Caboxyl esterases showed maximum activity at third instar stage of H. armigera (114.29 μg of α-NA formed/min/mg of protein). Non-denaturating Polyacrylamide gel electrophoresis spectrum revealed the presence of 10 esterase bands in Ludhiana region and 13 different bands in Mansa region.