Self-quenched fluorogenic protein substrates for the detection of cathepsin D and other protease activities

Self-quenched fluorogenic substrates for proteolytic enzymes have been prepared by alkylation of thiol groups in reduced bovine serum albumin with iodoacetamidofluorescein or iodoacetamidoeosin. Substrates immobilized by adsorption onto nitrocellulose membranes or by incorporation into agarose gel slabs are suitable for fluorescence zymography after electrophoretic separation of catalytically active proteases, including cathepsin D.