Preparation of coordinate file
The X-ray crystal structure of spike surface glycoprotein of SARS-CoV (PDB entry: 6CRV, resolution = 3.2 Å) and co-crystallized structure of SARS-CoV-2 RBD with human ACE2 Protein (PDB entry: 6M0J, resolution = 2.45 Å) was retrieved from Protein Data Bank (https:/www.rscb.org/pdb). The protein structure was prepared using the Discovery Studio Visualizer (version 3.1) and AutoDock Tools (ADT; version 1.5.4) through different steps viz. removal of water molecules and co-crystallized ligand, addition of missing hydrogen atoms, addition of Gasteiger-Marsili and Kollman charges, merging of non-polar hydrogens, and assignment of rotatable bonds. The file was then saved in pdbqt file format for further analysis.