<br/>The imidazole motif is widely encountered in biomolecules, and its biological role, for instance as a proton relay, is often linked to its abilility to form hydrogen bonds with water molecules. Detailed characterization of the hydration pattern of imidazole and its changes upon protonation is thus of high interest. We combine neutron scattering experiments with force field simulations to provide an unprecedented characterization of the solvation patterns of neutral and protonated imidazole at the atomistic level. We also show that neutron diffraction data can be used to assess the quality of force fields in molecular simulations. Simulations are in excellent agreement with the experimental neutron scattering data and we use them to provide an atomic scale interpretation of the neutron scattering patterns. Upon protonation, we clearly identify the signature of the reorganization in the hydration pattern caused by the change from one hydrogen bond donor and one hydrogen bond acceptor group for imidazole to two hydrogen bond donor groups for imidazolium.

Changes in the hydration structure of imidazole upon protonation: Neutron scattering and molecular simulations

254th National Meeting (2017)

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