Halogen bonding in ligand-receptor systems in the framework of classical force fields

Halogen bond is an important non-covalent interaction which is receiving a growing attention in the study of protein-ligand complexes. Many drugs are halogenated molecules and it has been recently shown that many halogenated ligands establish halogen bonds with biomolecules. As the halogen bond nature is due to an anisotropy of the electrostatic potential around halogen atoms, it is not possible to use traditional force fields based on a set of atom-centred charges to study halogen bonds in biomolecules. We show that the introduction of pseudo-atoms on halogens permits us to correctly describe the anisotropy of the electrostatic potential and to perform molecular dynamics simulations on complexes of proteins with halogenated ligands that reproduce experimental values. The results are compared with crystallographic data and with hybrid quantum mechanics/molecular mechanics calculations.