J . Am. Chem. SOC.1988, 110, 593-599 tions. The absorbance was monitored after each injection to assure that phenyl acetate was intact before the enzymic reaction began. The reaction was initiated with the injection of the enzyme in a 50-pL volume to bring the total to 1 mL. The irreversible inhibition of AChE in the presence of the substrate was studied under pseudo-first-order conditions with > 1000-fold excess of inhibitor over enzyme concentration to obtain a signal equal to
