The researchers used computer-aided drug design to identify N3—a mechanism-based inhibitor of the main protease (Mpro) of SARS-CoV-2. The team went on to describe a high-resolution crystal structure of Mpro in complex with N3. Once they had this structure, they could use it as a model to identify more lead Mpro inhibitors. They then tested more than 10,000 compounds using a FRET assay to identify six drug candidates that target Mpro and may hold promise in combating COVID-19.The SARS-CoV-2