The Toxicological Effects and Bioaccumulation of Fipronil in Larvae of the Mosquito Aedes aegypti in Aqueous Medium

In an immunoassay of a low molecular analytical target (AT), a rational design of a proper antibody specific to the AT was attempted by the application of computational chemistry. The assumption made was that a moiety of an AT and the corresponding hapten moiety of the proper antigen superimpose each other in terms of conformation. A miticide, pyridaben, was used as a case study. One of the methyl groups of each of two tert-butyl groups in pyridaben was modified to a carboxyl or hydroxymethyl group to give altogether two carboxyl and two hydroxymethyl compounds to be tested as haptens. For conformational analysis, each of the four haptens was combined with lysine and the conformation of the hapten-lysine complex was examined as a model of a hapten-protein conjugate. A stable and sterically acceptable conformation was first calculated by conventional molecular mechanics and then by Monte Cairo in detail, which gave 10 minimized conformations with the lowest energy. As the most optimized conformation, that with the lowest heat of formation was selected by calculation with MOPAC. Conformational superimposition of ATs and each complex was evaluated by the smallest root mean square calculated from the distances between the assigned pair of atoms. The inhibitory activity was determined by a competitive enzyme-linked immunosorbent assay as a parameter of the AT-antibody interaction. A good relationship was shown between the degree of superimposition and the inhibitory activity, except in one case, implying that candidate haptens can be computationally selected.