Brogdon_1987_Pestic.Biochem.Physiol_29_252

We have investigated the suitability of microplate assay methods for estimating the bimolecular rate constant ki and I50 for inhibition of acetylcholinesterase by selected organophosphates and carbamates in small portions of single-mosquito homogenates. Dilutions of homogenate up to 1:30 were used to measure these kinetic parameters. Absorbance values (or visual estimations) may be used to evaluate directly inhibitor potency in a particular assay. Practical values for these kinetic parameters may be rapidly and simply obtained using single concentrations of substrate and inhibitor. We determined variability of inhibited enzyme activities within a sample population of Anopheles gambiae using measurements from individual insects. The kinetic treatment used in analysis of microplate assay data is discussed together with the potential role of this technique in studies of enzyme inhibition phenomena associated with insecticide resistance.