The progress in the cholinesterase quantification methods

Determination of acetylcholinesterase and butyrylcholinesterase activity has become an important tool in drug design and discovery as well as in medicine and toxicology. There are a large number of compounds that are able to modulate cholinesterase activity. These compounds can be used for pharmacological management of various disorders (e.g., Alzheimer's disease, myasthenia Gravis). Moreover, organophosphate poisoning is frequently diagnosed via a cholinesterase activity assay. This broad variety of methods has been developed over the past decades for cholinesterase activity quantification.

This review provides a summary of the methods that are based on specific properties of cholinesterases and their interactions with native or artificial substrates. The authors also aim to provide an overview of different techniques used for the determination of quantitative cholinesterase activity. Specifically, the authors describe and discuss the manometric, potentiometric, titrimetric, photometric, fluorometric, and radioisotopic methods.

Existing methods are able to cover most of the problems that arise during cholinesterase activity determination. Colorimetry according to Ellman has proved to be the most useful and versatile approach. It may be used in various protocols for the determination of pesticide or nerve agent exposure or for the development of new drugs. Its possible improvement lies in optimization of hemoglobin-rich samples. The progress of the most common methods (including Ellman) depends on miniaturization and modern physical platforms (e.g., optical fibers, chip methods, or nanotechnologies).