Mca-AVLQSGFR-K(Dnp)-K-NH2 serves as a fluorogenic substrate specifically designed for the main protease (Mpro) of the severe acute respiratory syndrome coronavirus (SARS-CoV), also referred to as 3C-like protease (3CLpro). This substrate, upon enzymatic cleavage by SARS-CoV Mpro, liberates 7-methoxycoumarin-4-acetyl (Mca) which emits fluorescence. This fluorescence emission, with excitation/emission peaks at 328/420 nm respectively, facilitates the quantification of SARS-CoV Mpro's catalytic activity.