Partial Kinetic Analysis of Haemolymph Esterases From The Red Palm Weevil; Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae)

Fahmy, Nedal M.; Amin, Tarek R.

doi:10.21608/eajbsc.2019.104804

Partial Kinetic Analysis of Haemolymph Esterases From The Red Palm Weevil; Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae)

Document Type : Original Article

Authors

Nedal M. Fahmy ¹
Tarek R. Amin ²

¹ 1-Department of Pest Physiology, Plant Protection Research Institute (PPRI), Agricultural Research Center (ARC), Dokki, Giza, Egypt 2-Department of Biology, University Collage of Taymaa, University of Tabouk (ut), Kingdom of Saudi Areabia(Ksa)

² Department of Pest Physiology, Plant Protection Research Institute (PPRI), Agricultural Research Center (ARC), Dokki, Giza, Egypt

10.21608/eajbsc.2019.104804

Abstract

The paper represents a comprehensive study of the optimum subcellular fractions were prepared from the haemolymph of the seventh instar of the red palm weevil (RPW), Rhynchophorus ferrugineus Oliv. (Coleopter Curculionidae) to study some physicochemical characteristics of haemolymph esterases. The results showed that there were differences in characters between haemolymph α-esterases (hydrolyze alpha naphthyl acetate) and β-esterases (hydrolyze beta naphthyl acetate). The optimal pH and temperature were 8 and 50°C for α-esterases, respectively, and they were 7 and 35°C for β-esterases, respectively. Km (Michaelis constant) determined with alpha naphthyl acetate was 4X10^{-7 M}, and it was 13.3X10^{-6 M}for that determined with beta naphthyl acetate. V_max (maximum velocity) was 5.55 mg α-naphthol/min/mg protein and 1.66 mg β-naphthol/min/mg protein for α- and β-esterases, respectively. The effect of organic solvents on substrate hydrolysis was also discussed. The study provided biochemical optimized conditions for esterases activity, and with these ongoing studies, our further aim will be to develop new strategies for the red palm weevil control using disruptors of esterases as important detoxifying enzymes.

Keywords