Recently, Jin et al., have constructed a homology model for COVID-19 main protein and they used molecular docking to monitor whether the N3 binds with it. The docking showed that N3 binds with the COVID-19 main protease. Subsequently, the crystal structure of COVID-19  main protease in complex with N3 inhibitor  have been determined at 2.3A resolution and deposited in the protein data bank, where the N3 inhibitor binds with the residues of 164-168 in the long strand 155-168 residues, and with residues 189-191 of the loop connecting between second and third region.