Mca-PLGL-Dpa-AR-amide is a very sensitive FRET substrate for continuous assays and in situ determination of the matrix metalloproteinase activity. Cleavage at the Gly-Leu bond separates the highly fluorescent Mca group from the efficient 2,4-dinitrophenyl quencher, resulting in an increase in fluorescence intensity. The kcat/Km values for the punctuated metalloproteinase (MMP-7) and for gelatinase (MMP-2), e.g., are 1.7·10⁵ and 6.3·10⁵ M⁻¹s⁻¹, respectively.