Procedure for Detecting Atypical Serum Cholinesterase Using o-Nitrophenylbutyrate as Substrate

Abstract

A method has been developed for demonstrating atypical serum cholinesterase by means of the self-indicating substrate, o-nitrophenylbutyrate and the inhibitor succinyldicholine. The procedure was tested for atypical cholinesterase with 76 individuals, including 5 otherwise proven homozygotes and their immediate families. In all cases, it was possible to distinguish clearly those individuals homozygous for the usual and atypical cholinesterase as well as heterozygotes.

Prediction of drug sensitivity in individuals with atypical serum cholinesterase based on in vitro biochemical studies

“…The K,,,values for all compounds, except aspirin, have been reported previously. Our values are similar to those of Davies et al [20] for benzoylcholine, Kalow [6] and Foldes et al [21] for procaine and tetracaine, Bamford and Harris [8] for cy-naphthylacetate, and McComb et al [17] and Whittaker and Hardisty [22] for o-nitrophenylbutyrate, though strict comparisons cannot be made because buffer composition and temperature were, in many cases, different. Our observation that the affinities of atypical and usual cholinesterase are nearly identical for those substrates that are neutral esters provides an exception to the widely held generalization [20] that atypical cholinesterase has a lower affinity for all compounds.…”

“…Atypical cholinesterase appeared to have more o-nitrophenylbutyrate activity per unit of benzoylcholine activity that did usual cholinesterase. This result agrees with a similar observation reported by McComb et al [17]. Yet Fig.…”

Differentiation of Serum Cholinesterase Variants by Succinyldicholine Inhibition

“…Goedde, Held and Altland (1968) investigated the hydrolysis of succinyldicholine and succinylmonocholine by human cholinesterase and also the inhibition of benzoylcholine hydrolysis by these compounds. With a different substrate, o-nitrophenylbutyrate, McComb, LaMotta and Wetstone (1965) used succinyldicholine to differentiate the three usual/atypical phenotypes as did Garry (1971) employing butyrylthiocholine as substrate. In both these latter studies a clear differentiation was obtained correlating with dibucaine inhibition but slightly less effectively.…”