title: Vibrational density of states of hydration water at biomolecular sites: hydrophobicity promotes low density amorphous ice behavior.
abstract: Inelastic neutron scattering experiments and molecular dynamics simulations have been used to investigate the low frequency modes, in the region between 0 and 100 meV, of hydration water in selected hydrophilic and hydrophobic biomolecules. The results show changes in the plasticity of the hydrogen-bond network of hydration water molecules depending on the biomolecular site. At 200 K, the measured low frequency density of states of hydration water molecules of hydrophilic peptides is remarkably similar to that of high density amorphous ice, whereas, for hydrophobic biomolecules, it is comparable to that of low density amorphous ice behavior. In both hydrophilic and hydrophobic biomolecules, the high frequency modes show a blue shift of the libration mode as compared to the room temperature data. These results can be related to the density of water molecules around the biological interface, suggesting that the apparent local density of water is larger in a hydrophilic environment.
authors.affiliation: CNR-IOM c/o Institut Laue Langevin, 6 rue J. Horowitz BP156, F-38042 Grenoble, France. russo@ill.fr
authors.forename: Daniela
authors.initials: D
authors.lastname: Russo
authors.forename: José
authors.initials: J
authors.lastname: Teixeira
authors.forename: Larry
authors.initials: L
authors.lastname: Kneller
authors.forename: John R D
authors.initials: JR
authors.lastname: Copley
authors.forename: Jacques
authors.initials: J
authors.lastname: Ollivier
authors.forename: Stefania
authors.initials: S
authors.lastname: Perticaroli
authors.forename: Eric
authors.initials: E
authors.lastname: Pellegrini
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Gonzalez
mesh_terms: D001665:Binding Sites; D005998:Glycine / Q000031:analogs & derivatives; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007053:Ice; D007930:Leucine / Q000031:analogs & derivatives* / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D009502:Neutrons; D012542:Scattering, Radiation; D014732:Vibration; D014867:Water / Q000737:chemistry*
chemical_list: D007053:Ice; C492360:N-acetyl-leucine-methylamide; D014867:Water; C065960:acetylglycyl-N-methylamide; D007930:Leucine; D005998:Glycine