[Effect of substituted thiobutinylic esters of phosphorus thio acids and their saturated analogs on cholinesterases of different origins].

Studies have been made of the effect of organophosphorus inhibitors (OPI) containing butynilic group in the detectable part of the molecule, and of their saturated analogues on cholinesterases from different species of mammals and arthropods. In all cases without a single exception, acetylene compounds exhibited higher anticholinesterase effect than saturated ones. The value of "acetylene effect" varied to a great extent and depended on both the structure of OPI and the source of cholinesterase, these data indicating the existence of differences in the structure of the active site in cholinesterases investigated. The acetylene effect was always higher in ethylmercapto-substituted OPI than in chloride-substituted ones. Among thiophosphates, the highest (7,600) effect was found for cholinesterase of the spider mite in the case of dimethyl esters. Among thiophosphonates, exceptionally high (38,000) effect was noted for cholinesterase from the head of the domestic fly when methylthiophosphonates were compared. In this pair of compounds, the inhibitory constant k2 for the cholinesterase of the fly by acetylene derivative was equal to 1.1 . 10(9).