In the process of preparing receptors for modelling, the protein preparation facility [40] was used that included the operations of assigning bond orders, adding hydrogen, treating metals, treating disulfides, deleting waters and alleviating potential steric clashes, adjusting bond order, building missing heavy atom and formal charges, as well as minimizing energy with the OPLS2005 force field [41] and refining the protein by imposing the 0.3 Å RMSD limit as the constraint.