We have developed a highly sensitive, very rapid, extremely
simple assay for AChE activity, using the natural substrate,
acetylcholine. As shown in Figure 1, a series of coupled
enzyme reactions quickly translates the presence of active
AChE into a change in the luminance of the reaction. First
(reaction I), acetylcholine is hydrolyzed by the AChE to
yield acetate and choline. The acetate and choline then
enter a coupled enzyme reaction (reaction II) that results
in consumption of ATP, and finally the ATP concentration is
measured by the well-established luciferase method (reaction
III). These reactions can occur simultaneously, and the
result is generally obtained in five minutes or less.
Inhibitors of AChE are readily detected by an increase in
luminance due to reduced consumption of ATP.
The following reaction illustrates the
sequence of events if AChE inhibitors are present: