農薬代謝におけるグルタチオンS-トランスフェラーゼの役割

抄録

This review summarizes recent research on the metabolism of pesticides by GSH conjugation, the role of this reaction in pesticide selectivity in mammals and plants, and characteristics of GSH S-transferases. GSH conjugation occurs with organophosphorus insecticides, γ-BHC, organothiocyanate insecticides, s-triazine herbicides, thiocarbamate sulfoxides, fluorodifen, EDB and monofluoroacetic acid. GSH S-transferases are widely distributed in mammals, birds, fishes, insects, plants and microorganisms. The highest activity is found in the mammalian liver and microorganisms are low activity. Plant enzymes are very stable. GSH S-transferases from mammals and insects comprise a group of enzymes which have overlapping substrate specificities. Chemical structures possessing an electrophilic center, high SN reactivity, and the reactive center of low electron density can conjugate readily. The formation of a GSH conjugate destroys the biocidal properties of the parent molecule. The function of GSH S-transferases may be regarded as biological protection against electrophilic foreign compounds which have the capacity to bind to biological molecules with nucleophilic centers. The qualitative and quantitative differences in GSH S-transferases distributed in various organisms are closely associated with insecticide or herbicide selectivity and insecticide resistance. Dichloroacetamide antidotes act in corn to induce GSH and GSH S-transferase, resulting in rapid detoxication of thiocarbamate sulfoxides.