Fluorescent peptide synthesis and dye labeled peptides have been developped for in vivo biomedical imaging, protein binding and localization studies, etc. Fluorescent peptide synthesis is generally achieved though dye attachement to the peptide N-terminus directly (FITC always via be inserted an aminohexanoic acid (Ahx) or β-Ala linker between the fluorophore (fluoroscein) and the N-terminus of the peptide.). For fluorescent peptide synthesis with the dye linked at any position within the sequence or on C-terminus, the dye is attached to the Lys (or Cys) side chains. Genosphere Biotechnologies can provide many commonly used fluorescent and dyes peptides: such as FITC, FAM, TAMRA, NBD (7-nitrobenz-2-oxa-1, 3-diazole), Cy3, Cy5 and many more. Each fluorescence and dye labeled peptide delivered as a lyophilized powder in foil covered tube.
Fluorescence resonance energy transfer (FRET) is a process that allows the distance-dependent interaction between the excited states of two distinct dye-linked molecules to be detected. The excitation is transferred from a donor to an acceptor without emitting a photon. The assay is rapid, highly sensitive, and straightforward to perform.
FRET peptide synthesis include peptides combined attachment with fluorophores and quencher dyes. The fluorescence and quencher pair requires a significant overlap between the fluorescence emission spectrum of the fluorophore and the absorption spectrum of the quencher. Therefore, when the fluorophore and the quencher are conjugated to the same peptide at a limited distance, the quencher effectively prevents the emission of the fluorophore.
FRET peptide can be used to study peptidase specificity because they allow reactions to be monitored continuously, allowing the enzymatic activity to be determined rapidly. The FRET peptide bonds between the donor/acceptor pair can be cleaved, which generates a fluorescent signal to allow nanomolar concentrations of enzyme activity to be detected. When intact, FRET peptide quenches internal fluorescence; however, the cleavage of a peptide bond between the donor/acceptor pair releases a fluorescent signal that can be detected continuously, allowing enzyme activity to be quantified.
FRET peptide is used as suitable substrate in a variety of enzyme studies including kinetic and functional characterization of peptidases and proteases, screening and detection of novel proteolytic enzymes, or conformational investigation of peptide folding.