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Covidyte™ TF670

Coronaviruses (CoVs) can infect humans and multiple species of animals, causing a wide spectrum of diseases. In late 2019, a novel coronavirus, termed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was determined as a cause for several cases of respiratory disease (Covid-19). The virus rapidly spread worldwide. As of May 31st, 2022, more than 6.2 million people have died from coronavirus worldwide, and ~530 million cases have been reported. Currently, there are not any specific and effective options available for treating Covid-19. At present the clinical treatment of Covid-19 is mainly symptomatic combined with repurposing of already marketed antiviral drugs such as Remdesivir and antibiotics to treat secondary infections. There is an extremely urgent need for the development of specific antiviral therapeutics and vaccines against SARS-CoV-2. The coronavirus main protease, which plays a pivotal role in viral gene expression and replication through the proteolytic processing of replicase polyproteins, is an attractive target for anti-CoV drug design. The inhibition of viral proteases necessary for proteolytic processing of polyproteins has been a successful strategy in the treatment of human immunodeficiency virus (HIV) and hepatitis C respectively, proving the potential of protease inhibitors for the treatment of viral infections. Similarly, the main protease of SARS-CoV-2 is thought to be essential for viral replication and, therefore, is regarded as promising target for antiviral therapy of Covid-19. Covidyte™ TF670 is a peptide substrate containing 14 amino acid sequence (KTSAVLQSGFRKME) that can be cleaved by coronavirus proteases. The dark-FRET peptide contains Tide Quencher™ 5 (TQ5) as a quencher and Tide Fluor™ 5 (TF5) as a fluorescent donor on the N-and C-terminals respectively where the fluorescence of TF5 is effectively quenched by TQ5 when the peptide is intact. When the peptide is hydrolyzed by coronavirus proteases, the TF5 fragment generates significantly enhanced fluorescence since its fluorescence is no longer quenched by TQ5. The activity of coronavirus proteases can be effectively monitored by the fluorescence intensity of TF5. Covidyte™ TF670 is a robust high throughput screening tool for searching inhibitors of coronavirus proteases. TQ5-TF5 pair has been proven to an extremely effective FRET pair for developing FRET protease substrates. Comparing to the commonly used EDANS substrates (such as Covidyte™ EN450), the TF670 substrate has much stronger and longer fluorescence that is less interfered by colored compounds that often cause false positive hits.

Example protocol

PREPARATION OF STOCK SOLUTIONS

Unless otherwise noted, all unused stock solutions should be divided into single-use aliquots and stored at -20 °C after preparation. Avoid repeated freeze-thaw cycles.

Covidyte™ TF670 stock solution (200X)
Add 25 µL (For cat# 13540) or 250 µL (For cat# 13541) DMSO to Covidyte™ TF670 vial.
Note     Make single use aliquots and store at -20 °C.

PREPARATION OF WORKING SOLUTION

1. Covidyte™ TF670 working solution
Dilute substrate stock solution at 1:200 in 20 mM Tris buffer (pH 7.5) or buffer of your choice. Use 50 μL of substrate solution per assay in a 96-well plate.

2. Coronavirus proteases dilution
Dilute the coronavirus proteases as desired.

SAMPLE EXPERIMENTAL PROTOCOL

Sample Protocol for One 96-well plate
  1. Add 50 μL of EACH protease dilution to respective wells of the assay plate.
  2. Add 50 μL of Covidyte™ TF670 working solution to each protease dilution.
  3. Monitor the fluorescence increase with a fluorescence plate reader at Ex/Em = 640/680 nm (cutoff 660 nm). 
For kinetic reading: Immediately start measuring fluorescence intensity continuously and record data every 5 minutes for 30-120 minutes.
For end-point reading: Incubate the reaction at a desired temperature for 30 to 120 minutes, protected from light. Then measure the fluorescence intensity.

Spectrum

Product family

NameExcitation (nm)Emission (nm)Extinction coefficient (cm -1 M -1)Correction Factor (280 nm)
Covidyte™ EN45033645559000.107
Covidyte™ ED45033645559000.107
Covidyte™ IF67065667025000010.03

References

View all 45 references: Citation Explorer
Evaluating MERS-CoV Entry Pathways.
Authors: Qing, Enya and Hantak, Michael P and Galpalli, Gautami G and Gallagher, Tom
Journal: Methods in molecular biology (Clifton, N.J.) (2020): 9-20
Learning from the Past: Possible Urgent Prevention and Treatment Options for Severe Acute Respiratory Infections Caused by 2019-nCoV.
Authors: Morse, Jared S and Lalonde, Tyler and Xu, Shiqing and Liu, Wenshe Ray
Journal: Chembiochem : a European journal of chemical biology (2020): 730-738
SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor.
Authors: Hoffmann, Markus and Kleine-Weber, Hannah and Schroeder, Simon and Krüger, Nadine and Herrler, Tanja and Erichsen, Sandra and Schiergens, Tobias S and Herrler, Georg and Wu, Nai-Huei and Nitsche, Andreas and Müller, Marcel A and Drosten, Christian and Pöhlmann, Stefan
Journal: Cell (2020)
α-Ketoamides as Broad-Spectrum Inhibitors of Coronavirus and Enterovirus Replication: Structure-Based Design, Synthesis, and Activity Assessment.
Authors: Zhang, Linlin and Lin, Daizong and Kusov, Yuri and Nian, Yong and Ma, Qingjun and Wang, Jiang and von Brunn, Albrecht and Leyssen, Pieter and Lanko, Kristina and Neyts, Johan and de Wilde, Adriaan and Snijder, Eric J and Liu, Hong and Hilgenfeld, Rolf
Journal: Journal of medicinal chemistry (2020)
Structural Basis for Inhibiting Porcine Epidemic Diarrhea Virus Replication with the 3C-Like Protease Inhibitor GC376.
Authors: Ye, Gang and Wang, Xiaowei and Tong, Xiaohan and Shi, Yuejun and Fu, Zhen F and Peng, Guiqing
Journal: Viruses (2020)
Page updated on October 28, 2024

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Physical properties

Molecular weight

3620.33

Solvent

DMSO

Spectral properties

Correction Factor (280 nm)

0.027

Extinction coefficient (cm -1 M -1)

250000

Excitation (nm)

649

Emission (nm)

663

Quantum yield

0.271

Storage, safety and handling

H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22

Storage

Freeze (< -15 °C); Minimize light exposure
UNSPSC12171501

Platform

Fluorescence microplate reader

Excitation640 nm
Emission680 nm
Cutoff660 nm
Recommended plateSolid black
Proteases play essential roles in protein activation, cell regulation and signaling, as well as in the generation of amino acids for protein synthesis or utilization in other metabolic pathways. FRET protease substrates are widely used for detecting protease activities, in particular, for virus protease that often require a long peptide sequence for optimal binding such as coronavirus, HIV and HCV proteases. The internally quenched FRET peptide substrate is digested by a protease to generate the highly fluorescent peptide fragment. The fluorescence increase is proportional to the protease activity. Tide Quencher&trade; dyes have been proven to be the extremely effective quenchers for developing FRET protease substrates for high throughput screening applications together with our bright Tide Fluor&trade; and iFluor® dyes.
Proteases play essential roles in protein activation, cell regulation and signaling, as well as in the generation of amino acids for protein synthesis or utilization in other metabolic pathways. FRET protease substrates are widely used for detecting protease activities, in particular, for virus protease that often require a long peptide sequence for optimal binding such as coronavirus, HIV and HCV proteases. The internally quenched FRET peptide substrate is digested by a protease to generate the highly fluorescent peptide fragment. The fluorescence increase is proportional to the protease activity. Tide Quencher&trade; dyes have been proven to be the extremely effective quenchers for developing FRET protease substrates for high throughput screening applications together with our bright Tide Fluor&trade; and iFluor® dyes.
Proteases play essential roles in protein activation, cell regulation and signaling, as well as in the generation of amino acids for protein synthesis or utilization in other metabolic pathways. FRET protease substrates are widely used for detecting protease activities, in particular, for virus protease that often require a long peptide sequence for optimal binding such as coronavirus, HIV and HCV proteases. The internally quenched FRET peptide substrate is digested by a protease to generate the highly fluorescent peptide fragment. The fluorescence increase is proportional to the protease activity. Tide Quencher&trade; dyes have been proven to be the extremely effective quenchers for developing FRET protease substrates for high throughput screening applications together with our bright Tide Fluor&trade; and iFluor® dyes.
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