Ultraviolet spectrophotometric method for determination of cholinesterase activity with acetylcholine as a substrate.

An enzymatic method for the determination of serum cholinesterase (ChE) activity is described. The method is based on the liberation of acetate from acetylcholine as a substrate by ChE and the conversion of the acetate to acetylphosphate and ADP in the presence of ATP by acetate kinase. The produced ADP is coupled with pyruvate kinase and lactate dehydrogenase in the presence of phosphoenolpyruvate and NADH. The amount of NADH consumed is determined by absorbance at 340 nm. The reaction proceeds stoichiometrically, and the dilution curve is linear up to 3300 U/liter. The results obtained by this method show a good correlation with those obtained by the usual methods.