A mathematical treatment for the general case of enzyme inactivation by an inhibitor that breaks down in solution in a first-order reaction is presented. Cathepsin D was inactivated by fluorescein isothiocyanate with a Ki of 4.47μm. Kinetic constants were also determined for the inactivation of cathepsin D by 1,1-bis(diazoacetyl)-2-phenylethane, and the inactivation of pepsin C by diazoacetyl-dl-norleucine methyl ester.
