Peptidyl Acyloxymethyl Ketones as Activity-Based Probes for the Main Protease of SARS-CoV-2

The global pandemic caused by SARS-CoV-2 calls for a fast development of antiviral drugs
against this particular coronavirus. Chemical tools to facilitate inhibitor discovery as well as
detection of target engagement by hit or lead compounds from high throughput screens are
therefore in urgent need. We here report novel, selective activity-based probes that enable
detection of the SARS-CoV-2 main protease. The probes are based on acyloxymethyl ketone
reactive electrophiles combined with a peptide sequence including non-natural amino acids
that targets the non-primed site of the main protease substrate binding cleft. They are the first
activity-based probes for the main protease of coronaviruses and display target labeling within
in a human proteome without background. We expect that these reagents will be useful in the
drug development pipeline, not only for the current SARS-CoV-2, but also for other
coronaviruses.