Mca-SEVNLDAEFK(Dnp)-NH2 is a fluorogenic substrate featuring a 7-methoxycoumarin moiety whose fluorescence is quenched by the adjacent 2,4-dinitrophenyl group through resonance energy transfer. This compound serves as a probe for assessing peptidase activity; enzymatic cleavage of the amide bond separating the fluorophore and quencher results in increased fluorescence. It is particularly useful for quantifying the activity of BACE-1 [1].