Pesticide action and membrane fluidity Allosteric behavior of rat erythrocyte membrane‐bound acetylcholinesterase in the presence of organophosphorous compounds

It is well documented that the organophosphorous pesticides or their metabolites are powerful inhibitors of acetylcholinesterase with consequent disruption of nervous activity [l-2] . Variations in the interaction energies as low as 700 cal/mol would be enough to trigger significant changes in the Hill coefficient from membrane-bound enzymes (n-values) [3]. It was indicated that the cooperative behavior of several membrane-bound enzymes correlated with the membrane fluidity and that these relationships raised the possibility of evaluating changes in membrane fluidity [4] . This novel approach was illustrated in the case of cholesterol [5], cortisol, progesterone [6], insulin [6-71 and thyroid hormones and thyrotropin interplay [8]. In this work we offer biochemical evidence regarding a new molecular basis in the action of organophosphate agents on the membrane fluidity through studies