title: Proline induced disruption of the structure and dynamics of water.
abstract: We use quasi-elastic neutron scattering spectroscopy to study the diffusive motion of water molecules at ambient temperature as a function of the solute molar fraction of the amino acid, proline. We validate molecular dynamics simulations against experimental quasielastic neutron scattering data and then use the simulations to reveal, and understand, a strong dependence of the translational self-diffusion coefficient of water on the distance to the amino acid molecule. An analysis based on the juxtaposition of water molecules in the simulation shows that the rigidity of proline imposes itself on the local water structure, which disrupts the hydrogen-bond network of water leading to an increase in the mean lifetime of hydrogen bonds. The net effect is some distortion of the proline molecule and a slowing down of the water mobility.
authors.affiliation: Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia. dyu@ansto.gov.au gke@ansto.gov.au.
authors.forename: Dehong
authors.initials: D
authors.lastname: Yu
authors.forename: Marcus
authors.initials: M
authors.lastname: Hennig
authors.forename: Richard A
authors.initials: RA
authors.lastname: Mole
authors.forename: Ji Chen
authors.initials: JC
authors.lastname: Li
authors.forename: Cheryl
authors.initials: C
authors.lastname: Wheeler
authors.forename: Thierry
authors.initials: T
authors.lastname: Strässle
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Kearley
mesh_terms: D004058:Diffusion; D004735:Energy Transfer; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D033363:Neutron Diffraction; D011392:Proline / Q000737:chemistry*; D053838:Scattering, Small Angle; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D011392:Proline