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FRET Peptides

Custom and Catalog FRET Peptide Substrates

   Custom and Catalog FRET Peptides
  FIGURE. FRET caspase-1 substrate, Dabcyl-Tyr-Val-Ala-Asp-Ala-Pro-Val-EDANS (CASP-023). This fluorogenic caspase-1 substrate enables a continuous assay of caspase-1 helpful in the screening of inhibitory compounds (Km = 11.4 µM, kcat = 0.79 s-1)
  We have a wide range of ready-to-ship FRET peptide substrates available in our store. LEARN MORE 
  For custom peptide FRET substrates please submit a QUOTATION REQUEST  


Design & Synthesis of FRET and TR-FRET Peptide Substrates

CPC has experience with a wide range of protease peptide substrates including: Aggrecanase, ADAMs, ACE-2, APCE, 2A protease, BACE1, Calpains, Capases, Carboxypeptidases, Caspases, Cathepsins, Chymopapain, Complement component C1s, CMV protease, ECE-1, Factor Xa, Furin, Granzyme K, HCV protease, HIV protease, HRV1, h Kallikreins, Interferon alpha A, Lethal Factor Protease, Malaria Aspartyl Proteinase, MMPs, Pepsin, Plasmin, Plasmepsin II, Proteinases, Protein Tyrosin Phosphatase, Renin, SARS, TACE, Thrombin, TEV protease, Trypsin and West Nile Virus Protease.

FRET (Fluorescence Resonance Energy Transfer) is a distancedependent dipole-dipole interaction without the emission of a photon, which results in the transfer of energy from an initially excited donor molecule to an acceptor molecule. It allows the detection of molecular interactions in the nanometer range. FRET peptides are labeled with a donor molecule and an acceptor (quencher) molecule. In most cases, the donor and acceptor pairs are two different dyes. The transferred energy from a fluorescent donor is converted into molecular vibrations if the acceptor is a non-fluorescent dye (quencher). When the FRET is terminated (by separating donor and acceptor), an increase of donor fluorescence can be detected. When both the donor and acceptor dyes are fluorescent, the transferred energy is emitted as light of longer wavelength so that the intensity ratio change of donor and acceptor fluorescence can be measured. In order for efficient FRET quenching to take place, the fluorophore and quencher molecules must be close to each other (approximately 10-100 Å) and the absorption spectrum of the quencher must overlap with the emission spectrum of the fluorophore. While designing a donor-quencher FRET system, a careful comparison of the donor’s fluorescence spectrum with the quencher’s absorption spectrum is required.

The design and synthesis work in CPC for FRET and TR-FRET peptide substrates include modification of sequences, selection of donor/quencher pairs, improvement of FRET substrate solubility and quenching efficiency.


Table of Common FRET Pairs

Donor (Fluorophore) Excitation Emission Acceptor (Quencher)
EDANS (5-[(2-Aminoethyl) amino] naphthalene-1-sulfonic acid) 340 nm 490 nm Dabcyl (4-(4-Dimethylaminophenylazo)benzoyl)
Lucifer Yellow 430 nm 520 nm Dabsyl (4-(4-Diethylaminophenylazo)benzenesulfonyl)
Mca (7-Methoxycoumarin-4-yl)acetyl) 325 nm 392 nm Dnp (2,4-Dinitrophenyl)
Abz (2-Aminobenzoyl) 320 nm 420 nm pNA (para-Nitroaniline)
Abz (2-Aminobenzoyl) 320 nm 420 nm 3-Nitro-Tyr (3-Nitro-tyrosine)
Abz (2-Aminobenzoyl) 320 nm 420 nm 4-Nitro-Phe (4-Nitro-phenylalanine)
FITC (Fluorescein isothiocyanate) 490 nm 520 nm Dnp (2,4-Dinitrophenyl)
5-TAMRA (Carboxytetramethylrhodamine) 547 nm 573 nm QSY7
CP488 495 nm 519 nm CPQ2TM (proprietary structure)
5-FAM (5-Carboxyfluorescein) 492 nm 518 nm CPQ2TM (proprietary structure)
Cy5 647 nm 665 nm QSY21
Dansyl (5-(Dimethylamino)naphthalene-1-sulfonyl) 342 nm 562 nm 4-Nitro-Phe (4-Nitro-phenylalanine)
Trp (Tryptophan) 280 nm 360 nm Dnp (2,4-Dinitrophenyl)
Trp (Tryptophan) 280 nm 360 nm 4-Nitro-Z (4-Nitro-benzyloxycarbonyl)
(1) LaRock, Christopher N., et al. Science Immunology (2016) 100.200: 300.(2) Goupil, Louise S., et al. PLoS Negl Trop Dis 10.8 (2016): e0004893. (3) Welsh, J. D., et al. Journal of Thrombosis and Haemostasis 10.11 (2012): 2344-2353. (4) Doron, Lior, et al. PloS One 9.10 (2014): e111329. (5) Kwong, Gabriel A., et al. Proceedings of the National Academy of Sciences 112.41 (2015): 12627-12632. (6) Miles, Linde A., et al. PloS One 10.6 (2015): e0129103. (7) Jensen, Jesper Langholm, et al. Journal of Dairy Science 98.5 (2015): 2853-2860. (8) Shi, Jing, et al. Journal of Food Science 80.6 (2015): E1202-E1208. (9) Zhu, Shu, et al. Blood 126.12 (2015): 1494-1502. (10) Zhu, S., et al. Journal of Thrombosis and Haemostasis (2016). (11) Hershey, David M., et al. BioRxiv (2016): 047555. (12) Dudani, Jaideep S., et al. Advanced Functional Materials 26.17 (2016): 2919-2928.