Residues R853, R866, R869, E895 K925, R943, E944 and E1192 show larger favorable intermolecular interactions with the active site in the presence of Mg 2+ , with residues R853 and K925 showing the largest interactions (21.9 kcal/mol and 50.7 kcal/mol respectively). For the system with Mn 2+ , T849, I850, E856, K875, K947, R1190 and K1191 show significant favorable intermolecular interactions with the active site, with no specific residue having a very large contribution when compared to the interactions to the Mg 2+ system.