Fluorescent peptides, peptides with a reporter fluorescent dye, are valuable probes used in visualizing intracellular processes and molecular interactions at the level of single cells.¹ The fluorescent dye can be attached to the amino (N) or carboxy (C)-terminus, or in the case of FRET (Fluorescence or Förster resonance energy transfer) peptides, the two dyes (donor and acceptor) can be at the amino and carboxy termini or in the internal peptide sequence.

Leveraging our dual expertise in peptides and fluorescent dyes, AnaSpec is pleased to offer a broad selection of fluorescently labeled peptides labeled with our proprietary HiLyte Fluor™ dyes, as well as classic dyes (FAM, FITC, TAMRA).

Peptide substrates used in detection of enzyme activity can contain either a single dye or in the case of FRET, two dyes. In the intact fluorescent substrates, there is low fluorescence prior to enzyme hydrolysis. Upon recognition of the substrate by a specific enzyme and subsequent cleavage, the quenched fluorescence is recovered. Increase in fluorescence is correlated to enzyme activity.^2-3 AnaSpec’s  single dye-labeled fluorescent peptide selection include substrates for kinases, caspases, cathepsins, HDAC (histone deacetylase), calpain, kallikrein, and others. Our FRET peptides, generally consisting of a dye (donor) and a non-fluorescent quencher (acceptor), include substrates for MMPs, Aggrecanase-1, HCV, HIV, cathepsins, renin, ACE2, α and β-secretases and others.

For use as targeting probes

Fluorescent peptides have been used in in vivo or in vitro studies for visualizing cellular processes and molecular interactions.¹ In in vivo imaging, three-dimensional fluorescence images of the internal structures, especially of small animals, are produced. This technique requires the use of near infrared red (NIR) dyes since at higher wavelength, tissues do not absorb or scatter photons as strongly as when lower wavelength dyes are used.^2-3 An example is an RGD peptide, c[RGDyK(HiLyte Fluor™ 750)], that AnaSpec synthesized for J. Rey of the Univ. of South Florida. This peptide was shown to bind preferentially to organs that are known to be rich in integrin αvβ₃ (see poster for details)_. Another examples are the fluorescent cell penetrating peptides, FITC-LC-Antennapedia and TAMRA-labeled TAT (47-57), cat# 61211 (Fig. 1).

Figure 1. HeLa cells were incubated with OptiMEM medium containing 10 uM FITC-LC-Antennapedia, cat# 24175, 24176 (panel A) and 10 uM of TAMRA-labeled TAT (47-57), cat# 61211(B) for 1 h, washed and analyzed by fluorescence microscopy.

Related Products and Services

Full listing of SensoLyte® assay kits (majority FRET-based)

References:

1. Pap, EHW. et al. Exp. Cell Res. 265, 288 (2001).
2. Lakowicz, Joseph. Principles of Fluorescence Spectroscopy. New York: Springer, 2006.
3. Tung, C-H. Peptide Sci. 76, 391 (2004).