Each complex was visually examined with UCSF Chimera. Crystallization agents, uncoordinated ions and solvent molecules were deleted using its DockPrep functionality. Incomplete protein side chains were added using the Dunbrack rotamer library. Histidines were protonated according to their environment, and missing hydrogen atoms were added using the HBUILD 75 command of CHARMM. Protein chains situated further than 7 Å from the ligand were removed. When several copies of the ligand were present, we docked the one of the chain A and kept all other copies in the complex fixed during docking.