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Covidyte™ EN450

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). Even though most infected patients only suffer from mild symptoms such as fever and cough associated with a good prognosis, the disease can progress into fatal cases of pneumonia and acute respiratory failure, especially in older males with comorbidities. 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™ EN450 is a peptide substrate containing 14 amino acid sequence (KTSAVLQSGFRKME) that can be cleaved by coronavirus proteases. The dark-FRET peptide contains Dabcyl (quencher) and Edans (donor) on the N-and C-terminals respectively where the fluorescence of Edans is effectively quenched by Dabcyl when the peptide is intact. When the peptide is hydrolyzed by coronavirus proteases, the Edans fragment generates significantly enhanced fluorescence since its fluorescence is no longer quenched by Dabcyl. The activity of coronavirus proteases can be effectively monitored by the fluorescence intensity of Edans. Covidyte™ EN450 is a convenient tool for screening inhibitors of coronavirus proteases.

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™ EN450 stock solution (200X)
Add 25 µL (For cat# 13535) or 250 µL (For cat# 13536) DMSO to Covidyte™ EN450 vial.
Note     Make single use aliquots and store at -20 °C.

PREPARATION OF WORKING SOLUTION

1. Covidyte™ EN450 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™ EN450 working solution to each protease dilution.
  3. Monitor the fluorescence increase with a fluorescence plate reader at Ex/Em = 350/460 nm (cutoff 420nm). 
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)Quantum yieldCorrection Factor (280 nm)
Covidyte™ ED4503364555900-0.107
Covidyte™ TF6706496632500000.2710.027
Covidyte™ IF67065667025000010.2510.03
Covipyte™ EN4503364555900-0.107

References

View all 50 references: Citation Explorer
A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility.
Authors: Wang, Qiong and Qiu, Ye and Li, Jin-Yan and Zhou, Zhi-Jian and Liao, Ce-Heng and Ge, Xing-Yi
Journal: Virologica Sinica (2020)
Prediction of the SARS-CoV-2 (2019-nCoV) 3C-like protease (3CL pro) structure: virtual screening reveals velpatasvir, ledipasvir, and other drug repurposing candidates.
Authors: Chen, Yu Wai and Yiu, Chin-Pang Bennu and Wong, Kwok-Yin
Journal: F1000Research (2020): 129
Structural and biochemical characterization of SADS-CoV papain-like protease 2.
Authors: Wang, Lu and Hu, Weihua and Fan, Chengpeng
Journal: Protein science : a publication of the Protein Society (2020): 1228-1241
Potential inhibitors against 2019-nCoV coronavirus M protease from clinically approved medicines.
Authors: Liu, Xin and Wang, Xiu-Jie
Journal: Journal of genetics and genomics = Yi chuan xue bao (2020)
Unrevealing sequence and structural features of novel coronavirus using in silico approaches: The main protease as molecular target.
Authors: Ortega, Joseph Thomas and Serrano, Maria Luisa and Pujol, Flor Helene and Rangel, Hector Rafael
Journal: EXCLI journal (2020): 400-409
Page updated on October 28, 2024

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Physical properties

Molecular weight

2584.98

Solvent

DMSO

Spectral properties

Correction Factor (280 nm)

0.107

Extinction coefficient (cm -1 M -1)

5900

Excitation (nm)

336

Emission (nm)

455

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

Excitation350 nm
Emission460 nm
Cutoff420 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.
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.
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.
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