Abstract

Several scale modifications are given of a simple radiometric method for determining the activity of acetylcholinesterases. Enzyme samples of 0.01 to 100 µl are used to reconstitute a dried buffer-substrate containing radioactive acetylcholine. Labeled acetate produced by enzymatic hydrolysis of acetylcholine is extracted into an organic solvent and is counted by liquid scintillation spectrometry. The potential of the method is illustrated with two enzyme preparations, highly purified acetylcholinesterase from the electric eel and esterases present in homogenates of the rat brain cortex. Quantities of brain tissue between 0.1 mµg and 3 mg were readily studied.