An internally quenched fluorogenic 11-mer peptide that acts as a sensitive and selective substrate for cathepsins D and E (Kcat/Km = 15.6 μM-1s-1 and 10.9 μM-1s-1 for rat gastric cathepsin D and human erythrocyte cathepsin E, respectively), but not cathepsins B, H, or L . Cleavage occurs between Phe-Phe residues and results in enhanced fluorescence. A useful tool for inhibitors screening or for the determination of cathepsins D and E activities in crude extracts of various tissues and cell lysates. MCA = (7-Methoxycoumarin-4-yl)acetyl Excitation max.: ~328 nm, Emission max.: ~393 nm |