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Definition
Fluorescence resonance energy transfer (FRET) is a distance-dependent interaction between the electronic excited states of two dye molecules in which excitation is transferred from a donor molecule to an acceptor molecule without emission of a photon1. Following are some of the standard dye combinations used: a)Fluorescein and Dabcyl or Dabsyl b) Fluorescein and Tamra c) Methoxy-coumarin-acetic-acid(MCA) and 2,4-Dinitrophenyl(DNP).

Discovery
The first internally quenched fluorescent peptide reported was a substrate for angiotensin I-converting enzyme (ACE), namely Abz-Gly-Phe(NO2)-Pro where the fluorescence of the N-terminal ortho-amino benzoic acid (Abz) was quenched by the p-nitro-phenylalanine [Phe(NO2)] group (Carmel and Yaron 1978) 2.  A new generation of fluorescence-quenched substrates was developed by Chagas et al., (1991), using the FRET peptide concept described substrates for tissue and plasma kallikrein containing Abz as the fluorescent group and EDDnp (2,4-dinitrophenyl ethylenediamine) as the quencher group. The FRET peptides introduced by Chagas et al., (1991) was a breakthrough in the study of proteases’ specificity, and the synthesis of different Abzpeptidyl-EDDnp sequences provided the opportunity for us to study the activity of various endopeptidases such as human rennin3.

Structural Characteristics
FRET peptides are labelled with two dye molecules. These can be identical, but in most applications, different dyes are commonly used. FRET describes the transfer of energy from an initially excited donor (dye 1) to an acceptor (dye 2). Typically, this donor emits light at a wavelength λd that overlaps with the absorption wavelength λa of the acceptor. If donor and acceptor dye are in close proximity (10 – 100 Å),

this energy transfer happens in one of two ways, depending on the chemical structure of the acceptor:
a) the transferred energy is converted to molecular vibrations (acceptor is dark quencher)
b) the transferred energy is emitted as light with a longer wavelength (acceptor is fluorescent).

Mode of Action
In a FRET peptide fluorescent donor group attached to one of the amino acid residues of the peptide transfers energy to a quenching acceptor attached to another residue in the sequence following the resonance mechanism.  This process occurs whenever the emission spectrum of the fluorophore overlaps with the absorption spectrum of the acceptor (Sapsford et al., 2006)4. The FRET peptides exhibit internal fluorescence quenching when intact, but cleavage of any peptide bond between the donor/acceptor pair liberates fluorescence that can be detected continuously, allowing a quantitative measurement of the enzyme activity.

Functions
Fluorescence Energy Resonance Transfer (FRET) peptides are an excellent alternative for enzyme kinetic studies and for analysis of the enzymatic activity in biological fluids, crude tissue extracts or on the surface of cells in culture.

FRET peptides are used as suitable substrates in enzyme studies, such as:

1. Functional characterization of peptidases / proteases / kinases / phosphatases.

2. Kinetic characterization of peptidases / proteases / kinases / phosphatases.

3. Screening and detection of new proteolytic enzymes.

4. They can be used for conformational investigation of peptide folding.

References

1.     Hossain MA, Mihara H, Ueno A (2003). Fluorescence resonance energy transfer in a novel cyclodextrin-peptide conjugate for detecting steroid molecules. Bioorg Med Chem Lett., 13(24):4305-4308.

2.     Carmel A, Yaron A (1978). An intramolecularly quenched fluorescent tripeptide as a fluorogenic substrate of angiotensin-I-converting enzyme and of bacterial dipeptidyl carboxypeptidase. Eur J Biochem., 87(2):265-273.

3.     Chagas JR, Juliano L, Prado ES (1991). Intramolecularly quenched fluorogenic tetrapeptide substrates for tissue and plasma kallikreins. Anal Biochem., 192(2):419-425.

4.     Sapsford KE, Berti L, Medintz IL (2006). Materials for fluorescence resonance energy transfer analysis: beyond traditional donor-acceptor combinations. Angew Chem Int Ed Engl., 45(28):4562-4589.

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If you are unable to find your desired product please contact us for assistance or send an email to info@biosyn.com

 
Product Name Catalog # Unit Price/Unit 
2837b, Hemoglobin Fragment, Plasmepsin II (PM II) substrate, EDANS/ DABCYL
EDANS - CO - CH2 - CH2 - CO - ALERMFLSFP - Dap(DABCYL)OH
14504-01 1 mg $237 cart inquire
360 MMP FRET Substrate I
Dnp-PLGLWAr-CONH2
11074-01 1 mg $220 cart inquire
360 MMP FRET Substrate II
Dnp-PLALWAR
11077-01 1 mg $210 cart inquire
360 MMP FRET Substrate III
Dnp-PLGMWSR
11079-01 1 mg $210 cart inquire
360 MMP FRET Substrate IV
Dnp-PYAYWMR
11080-01 1 mg $210 cart inquire
360 MMP FRET Substrate V
Dnp-RPLALWRS
11081-01 1 mg $210 cart inquire
360 MMP FRET Substrate VI
Dnp-PLAYWAR
11083-01 1 mg $210 cart inquire
390 MMP FRET Substrate I
Mca - PLGL - Dpa - AR - NH2
14505-01 1 mg $120 cart inquire
390 MMP FRET Substrate I
Mca - PLGL - Dpa - AR - NH2
14506-05 5 mg $391 cart inquire
390 MMP FRET Substrate II
Mca - PLGL - Dpa - AR
14507-05 5 mg $380 cart inquire
390 MMP FRET Substrate IV
Mca - P - Cha - G - Nva - HA - Dpa - NH2
14508-05 5 mg $380 cart inquire
490 MMP FRET Substrate III
DABCYL - RPLALWRS - EDANS
14509-01 1 mg $215 cart inquire
520 MMP FRET Substrate I
QXL® 520 - PLGLWArK(5 - FAM) - NH2
14511-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate III
QXL® 520 - PLGC(Me)HAr - K(5 - FAM) - NH2
14512-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate IX
QXL® 520 - RPLALWRK(5 - FAM) - NH2
14513-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate V
5 - FAM - PLGL - Dap(QXL® 520) - AR - NH2
14514-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate VI
QXL® 520 - PLGMWSRK(5 - FAM) - NH2
14515-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate VII
QXL® 520 - PYAYWMRK(5 - FAM) - NH2
14516-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate XI
5 - FAM - P - Cha - G - Nva - HA - Dap(QXL® 520) - NH2
14517-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate XII
5 - FAM - RPKPYA - Nva - WM - K(QXL® 520) - NH2
14518-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate XIII
5 - FAM - RPKPVE - Nva - WRK(QXL® 520) - NH2
14519-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate XIV
QXL® 520 - γ - Abu - P - Cha - Abu - Smc - HA - Dab(5 - FAM) - AK - NH2 (Smc=S - Methyl - L - cysteine)
14520-001 0.1 mg $154 cart inquire
520 MMP FRET Substrate XV
QXL® 520 - γ - Abu - PQGL - Dab(5 - FAM) - AK - NH2
14521-001 0.1 mg $154 cart inquire
580 MMP FRET Substrate I
QXL® 570 - KPLA - Nva - Dap(5 - TAMRA) - AR - NH2
14522-001 0.1 mg $154 cart inquire
5 - FAM MMP FRET Peptide Fluorescence Standard I
5-FAM-PL
11109-001 0.1 mg $245 cart inquire
5 - FAM MMP FRET Peptide Fluorescence Standard I
5 - FAM - PL
14510-001 0.1 mg $120 cart inquire
Bacterial Sortase Substrate I FRET
DABCYL - LPETG - EDANS
14523-01 1 mg $232 cart inquire
C2 substrate, (DABCYL/EDANS)
DABCYL -SLGRKIQI-EDANS
11120-01 1 mg $350 cart inquire
Cathepsin D and E FRET Substrate
Mca - GKPILFFRLK(Dnp) - r - NH2
14524-01 1 mg $138 cart inquire
Cathepsin L Substrate
FITC-LC-EKARVLAEAAK(DABCYL)
11066-01 1 mg $325 cart inquire
Cls Substrate, C2 (5 - FAM/ QXL® 520)
5 - FAM - SLGRKIQIQ - K(QXL® 520) - NH2
14525-005 0.5 mg $226 cart inquire
Cls Substrate, C2 (Abz/Dnp)
2Abz - SLGRKIQIK(Dnp) - NH2
14526-01 1 mg $176 cart inquire
CMV Protease FRET Substrate I
11065-01 1 mg $350 cart inquire
HCV (Hepatitis C Virus) NS3/4A Protease Substrate
Ac - DE - Dap(QXL® 520) - EE - Abu - ψ - [COO]AS - C(5 - FAMsp) - NH2
14527-01 1 mg $721 cart inquire
HCV Protease FRET Substrate (RET S1)
Ac - DE - Dap(QXL® 520) - EE - Abu - ψ - [COO]AS - C(5 - FAMsp) - NH2
14528-01 1 mg $578 cart inquire
Hemoglobin, 2837a, Malaria FRET substrate III
DABCYL-GABA-ALERMFLSFP-EDANS
11123-01 1 mg $345 cart inquire
Hemoglobin, 3037a, Malaria FRET Substrate II
DABCYL-GABA-ERMFLSFP-EDANS
11122-01 1 mg $330 cart inquire
HIV Protease FRET Substrate I
11064-01 1 mg $340 cart inquire
HIV Protease FRET Substrate I
DABCYL - GABA - Ser - Gln - Asn - Tyr - Pro - Ile - Val - Gln - EDANS
14529-01 1 mg $226 cart inquire
Malaria Aspartyl Proteinase FRET Substrate I
11068-01 1 mg $330 cart inquire
Renin FRET Substrate I
11067-01 1 mg $330 cart inquire
Renin FRET Substrate I
DABCYL-g-Abu-IHPFHLVIHT-EDANS
14530-01 1 mg $215 cart inquire
TACE FRET Substrate I
11069-01 1 mg $345 cart inquire
TNO211
DABCYL - (γ - Abu) - PQGL - E(EDANS)AK - NH2
14531-01 1 mg $248 cart inquire

Biosynthesis Inc.