Organophosphorus pesticides stress deranged kinetic values of a few midgut carbohydrases of naiad of Trithemis aurora (burm.) (Odonata: Libellulidae)

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The 40 Hrs. treatment of last instar naiad of Trithemis aurora (Burm.) in Chlorphyriphos and Quinalphos pesticides concentrations (LC50 = 5.12 ×10-7 ppm and 7.6 × 10-8 ppm) has shown significant variations in the enzyme kinetic parameters and arrested the enzymatic activity in the midgut tissue of last instar naiad of T. aurora causing deleterious effect on various carbohydrases at standard temp. and pH value. The midgut amylase ( μ and β amylase) showed the change in the velocity of enzymatic reaction under LC50 conc. of chlorpyriphos. The data of initial velocity and substrate concentration were processed to achieve their reciprocal values. These values were plotted and a characteristic Lineweaver Burke straight line was observed from the graph and values of maximum reaction velocity (Vmax) and Michaelis Menten constants (km) were assessed. The present organophosphorus pesticide showed an inhibitory impact on midgut amylase reaction velocity. The double reciprocal plot of initial velocity and substrate concentration after exposing the enzyme under LC50 conc. of chlorphyriphos resulted in varied Vmax and Km. values. These carbohydrase on treatment with LC50 conc. of chlorphyriphos showed an inhibitory change in the reaction velocity. The 1/V and 1/S values were plotted to achieve a characteristic Lineweaver – Burke pattern of Vmax and km values obtained as 5.0 × 10-2 [M] and 2.0 under LC50 chlorphyriphos stress for α amylase. The km and Vmax values were obtained from 0.625 × 10-3 [M] to 1.25 × 10-2 [M] for various other midgut carbohydrases with Vmax value obtained from 0.28 to 5.0 under chlorpyriphos stress. The Quinalphos inhibited the enzymatic efficiencies of various carbohydrases severely and changed Km and Vmax values were found under the pesticidal stress and found as potent uncompetitive inhibitor for enzymes as values compared to the controlled enzymatic reactions by deranging the kinetic values. The Km values determined as on 1/V and 1/S basis found deranged from 1.66 × 10-3 [M] to 10 × 10-2 [M]. The Vmax values were found in a range of 0.41 to 3.3 under LC50 Quinalphos stress for midgut hydrolases. The analysis of enzymec kinetic values revealed the great inhibitory and deranged activities of various carbohydrases under both the pesticide constrain. The present toxicants were found to change the enzymatic velocity negatively. The LC50 concentrations of these toxicants were sufficient to inhibit the activity of present hydrolases as α and β amylase, α glucosidase, α galactosidase, β galactosidase, β frictosidase and α trehalase obtaining a meaningful Lineweaver – Burke line of plotted reciprocals of data of reaction velocity and substrate concentration.