Balashova_1980_Zh.Evol.Biokhim.Fiziol_16_244

Studies have been made on the effect of organophosphorus inhibitors on cholinesterases (CHe) from mammals (human and rabbit erythrocytes, mice brain) and arthropods (fly, spring grain aphid, rice weevil and spider tick). Organophosphorus inhibitors were presented by dialkylthiophosphates which contained normal or branching alkyls in the phosphoryl part of their molecule and lupinine or epilupinine residue in the other part of the latter. Increasing the length of alkyl in lupinine derivatives increased their inhibitory effect with respect to mammalian CHe, but decreased it in relation to all the investigated arthropod CHe. For epilupinine derivatives, the same relationship was found with mammalian CHe, being absent in arthropod enzymes. These data indicate the existence of significant differences in spatial structure of both esterase and anionic centers of the enzyme from mammals and arthropods. In arthropod CHe, hydrophobic regions of the esterase center are less developed that in mammalian CHe. The distance between the anionic and esterase centers of CHe is presumably different in the enzymes from different species.