Covipyte™ 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. Covid-19 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. Coronavirus is a single-stranded RNA positive-strand envelope type B coronavirus. Like the other two coronaviruses that cause SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome), SARS-CoV-2 encodes non-structural, structural, and accessory proteins. Non-structural proteins include 3-chymotrypsin-like protease (3CLpro), papain-like protease, helicase, and RNA-dependent RNA polymerase (RNA -dependent RNA polymerase (RdRp). Structural proteins include spike glycoproteins. Papain in coronavirus operates on more than 11 cleavage sites on the large polyprotein 1ab. Processing of polyproteins translated from viral RNA is essential, therefore, the main proteases are identified as an attractive drug targets for preventing virus imitation. Papain-like protease (PLpro) of coronaviruses carries out proteolytic maturation of non-structural proteins that play a role in replication of the virus and performs deubiquitination of host cell factors to scuttle antiviral responses. Covipyte™ EN450 is a peptide substrate containing 9 amino acid sequence (RELNGGAPI) that can be cleaved by coronavirus PLpro. The dark-FRET peptide contains Edans (donor) and Dabcyl (quencher) 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. Covipyte™ EN450 is a convenient tool for screening and studying kinetics of PLpro inhibitors.