[Estimation of anticholinesterase activity in reversible inhibitors of cholinesterase hydrolysis]

The kinetic analysis of cholinesterase interaction with reversible inhibitors was carried out. It has shown that the existing methods for definition of the type of reversible inhibition of enzyme reactions are not reliable. For example, mixed inhibition with the correlation between the competitive inhibition constant (Kl) and noncompetitive inhibition constant (K'i) less than 0.04, is identified as competitive inhibition. Apparently the ideal competitive inhibition with Ki/Ki = 0 does not exist in reality, because it is unlikely for a reversible inhibitor to decrease the process of the substrate sorption on a catalytical centre of cholinesterase not affecting the deacetylation rate. For objective evaluation of efficiency of reversible inhibitors it is suggested to determine the generalized inhibitory constant Ki at the cholinesterase hydrolysis in acetylcholine or acetylthiocholine. The data about anticholinesterase activity of carbonic and sulfoesters of lupinin are adduced.