FRET study in oligopeptide-linked donor-acceptor system in PVA matrix.

An oligopeptide: Lys-Gly-Pro-Arg-Ser-Leu-Ser-Gly-Lys-NH2 , cleaved specifically by a matrix metalloproteinase 9 (MMP-9) at the Ser-Leu bond, was labeled on the ε-NH2 groups of lysine with donor (5, 6 TAMRA) and acceptor (HiLyte647) dye. The donor control was a peptide labeled with 5, 6 TAMRA only on the C-terminal lysine, and the acceptor control was free HiLyte647. Following three products were studied by dissolving in 10% (w/w) poly(vinyl alcohol) and dried on glass slides forming 200 micron films. Absorption spectra of the films show full additivity of donor and acceptor absorptions. A strong Fluorescence Resonance Energy Transfer (FRET) with an efficiency of about 85% was observed in the fluorescence emission and excitation spectra. The lifetime of the donor was shorter and heterogeneous compared with the donor control.