Kinetic Evidence of Plant-esterase Inhibited by Organophosphours Pesticides

摘要

Although there are many studies about the inhibition of organophosphours pesticides（OPs） against plant-esterase，most of which emphase on the effect of reaction time，temperature and PH，the toxicity of pesticides against plant-esterase with respect to enantioselectivity has so far received limited attention. In this study，the kinetic constants of plant-esterase inhibited by the racemate and enantiomers of malaoxon，isomalathion，and methamidophos were investigated. The inhibition on plant-esterase tested with optically pure stereoisomers of malaoxon，isomalathion and methamidophos showed its stereoselectivity. As for malaoxon，and isomalathion，R-configure were more toxic than the S-configure enantiomers to test esterase. In contrast，the S-methamidophos was a stronger inhibitor to test esterase. These results suggest that the biotoxicity of chiral OPs to nontargeted organisms is enantioselective and therefore should be reevaluated with their pure enantiomers.