Oxime reactivation of erythrocyte cholinesterase inhibited by ethyl p-nitrophenyl ethylphosphonate

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Abstract
Reactivation of erythrocyte cholinesterase inhibited by ethyl p-nitrophenyl ethylphosphonate (armine) was studied with NN[image]-dimetnylenebis-(4-hydroxyiminomethylpyridinium bromide) (C2-oxime), NN[image]-trimethylenebis-(4-hydroxyiminomethylpyridinium bromide) (C3-oxime), NN[image]-tetramethylene-(4-hydroxyiminomethylpyridinium bromide) (C4-oxime) and NN[image]-pentamethylenebis-(4-hydroxyiminomethyl-pyridinium bromide) (C5-oxime) as reactivators. The kinetics of reactivation were consistent with a reaction of the type: Phosphorylated enzyme + oxime [image] free enzyme + phosphorylated oxime and bimolecular rate constants for reactivation were calculated from the corresponding differential equations. Of the four oximes studied C2-oxime was least effective and the other three oximes were about equally effective reactivators. Reactivation of armine-inhibited cholinesterase by C3-oxime was also studied in the presence of substrate. This reaction was first-order with respect to inhibited enzyme, and slower than in the absence of substrate.