“…Using the data filed in the Protein Data Bank ( https://www.rcsb.org/ ) database, the structure of the COVID-19 virus main protease (M pro ) was obtained, identified in the repository as The crystal structure of COVID-19 main protease in complex with an inhibitor N3 PDB ID: 6LU7 , composed of three domains, domain I (residue 8–101), domain II (102–184), domain III (201–303), and a long loop (185–200) binding domain II to domain III; its structure was filed in the Protein Data Bank with a resolution of 2.16 Å, determined from X-ray diffraction, classified as viral protein, Bat SARS-like coronavirus organism, and Escherichia coli BL21(DE3) expression system [ 6 ]. In the process of preparing the SARS-CoV-2 main protease, all residues were removed and polar hydrogens were added [ 7 , 8 ], producing favorable protonation states for molecular docking [ 9 ].…”