We prepared the chosen receptor PDB structures using the following steps. First, pdbfixer 1.4 was used to remove the ligand and the water molecules and to add the missing heavy atoms to the receptor structure. Next, we protonated the residues of the receptors at a pH of 4.5 and renamed the residue/atom names according to the AMBER naming scheme using PDB2PQR web server . The resulting pqr files were converted to PDB files using Parmed 2.7.4.