Acetylcholinesterase (AChE) technology

AChE assays are developed with Ellman’s reagent, which contains acetylthiocholine as a substrate. The final product of the enzymatic reaction (5-thio-2-nitrobenzoic acid), is bright yellow and can be read at 405-414 nm.

The use of AChE as enzymatic label for ELISA is patented by the French academic research Institute CEA, and Bertin Bioreagent has expertise to develop and produce ELISA kits using this technology.

Structure of a human Acetylcholinesterase (Kryger et al 2000)

AChE offers several advantages compared to enzymes conventionally used in ELISA:

Kinetic superiority and high sensitivity: AChE shows true first-order kinetics with a turnover of 64,000 sec-1. That is nearly 3 times faster than Horse Radish Peroxidase (HRP) or alkaline phosphate. AChE allows a greater sensitivity than other labelling enzymes.

Low background: non-enzymatic hydrolysis of acetylthiocholine in buffer is essentially absent. So, AChE allows a very low background and an increased signal/noise ratio compared to other substrate of enzymes, which are inherently unstable.

Wide dynamic range: AChE is a stable enzyme and its activity remains constant for many hours as, unlike other enzymes, its substrate is not triggering suicide inactivation. This permits simultaneous assays of high diluted and very concentrated samples.

Versatility: AChE is a completely stable enzyme, unlike peroxidase which undergoes suicide inhibition. Thus, if a plate is accidentally dropped after dispatch of the AChE substrate (Ellman’s reagent), one only needs to wash the plate, add fresh Ellman’s reagent and proceed with a new development. Otherwise, the plate can be stored at +4°C while waiting for technical advice from the Bioreagent Department.