LAUSR

Abstract Two highly sensitive fluorescent dye-labelled peptide indicators for metalloproteinase 9 (MMP-9) activity were designed and tested in vitro. Excellent sensitivity of these indicators is achieved by careful selection of the amino acid sequence corresponding to the substrate recognition preference of MMP-9. The phenomenon of Forster resonance energy transfer (FRET) is applied for detection of the peptide cleavage by MMP-9. FRET occurs between fluorescent dyes AMCA (donor) and TAMRA (acceptor) bound to the flexible peptide fragments differing in the donor acceptor separation distance. Enzymatic hydrolysis of the peptide leads to a significant weakening of energy transfer and increased donor fluorescence intensity. The enzyme action efficiency is higher for the longer proline-rich peptide which is reflected in the results of steady-state fluorescence studies. In particular, the use of longer peptide allows shorter detection time of MMP-9 (about 20–30 min). The possible reasons for this effect are discussed.