SARS-CoV-2 Protease Assays for Testing of new COVID-19 Therapeutics

In today’s global COVID-19 pandemic crisis, protease studies are more important than ever, since they are essential for virus infections. Existing protease inhibitors are now being added to clinical trials for COVID-19, and more specific proteases have been under special investigation as new strategical targets to prevent and cure COVID-19 infections. These targets include ACE2, TMPRSS2 (Transmembrane protease serine 2) that aid the virus entry into host cells, and Main Protease (Mpro) that is indispensable for virus replication and infection process.  

To support the drug discovery community in the challenge to identify efficacious COVID-19 drugs, we have developed specific assays targeting proteases that are essential for SARS-CoV-2 virus entry and replication.

  • Fluorescence-based activity assays
  • Low and large scale screening, as well as high-throughput screening options, are available

  • Full protease panel screening is available for off-target analysis.

Proteases as Targets against SARS-CoV-2

Host proteases furin and TMPRSS2 play a vital role in the pathogenesis and replication of SARS-CoV-2 by cleaving the spike protein to enable membrane fusion for virus entry. Cathepsin L further primes the spike protein in the acidic environment of endosomes. PLpro and Mpro are viral proteases required for virus replication. They proteolytically process the polyprotein, which is a prerequisite for virus assembly. PLpro is also known to interfere with the anti-viral immune response of the host cell.

The role of proteases in the replication of SARS-CoV-2 including intervention points for testing of new covid-19 drug candidates as example for coronavirus treatment

List of Targets

table of SARS-CoV-2 related protease assays
Target Synonyms Data
Cathepsin L CTSL, CTSL1 Data sheet
Furin FUR, PACE, PCSK3 Data sheet
Mpro 3CLpro Data sheet
PLpro NSP3, Papain-Like cysteine protease Data sheet
TMPRSS2 Transmembrane protease serine 2, PRSS10 Data sheet
TMPRSS6 Transmembrane protease serine 6, matriptase 2 Data sheet
ACE2 angiotensin I converting enzyme 2
Cathepsin B APP secretase, Cathepsin B1, CATB, CTSB, CPSB Data sheet

Assay Details

Study Example PLpro

The papain-like protease (PLpro) is responsible for cleavage of the coronavirus polyprotein necessary for virus assembly. PLpro also suppresses the host innate immune through the reversal of ubiquitination and ISGylation events. We offer the investigation of the proteolytic activity of PLpro for deubiquitination and for proteolysis of a peptide.


example study for testing compounds against coronavirus SARS-CoV-2 protease PLpro for drug discovery for treatment of covid-19

The PLpro assay allows for screening compounds using a fluorogenic substrate, either Z-RLRGG-AMC or Ubiquitin-AMC. PLpro cleaves the substrate for the release of AMC and the resulting fluorescence can be quantified with a luminometer for readout of PLpro enzymatic activity.