title: Retardation of Bulk Water Dynamics by Disaccharide Osmolytes.
abstract: The bioprotective nature of disaccharides is hypothesized to derive from the modification of the hydrogen bonding network of water which protects biomolecules through lowered water activity at the protein interface. Using ultrafast fluorescence spectroscopy, we measured the relaxation of bulk water dynamics around the induced dipole moment of two fluorescent probes (Lucifer Yellow Ethylenediamine and Tryptophan). Our results indicate a reduction in bulk water reorganization rate of approximately 30%. We observe this retardation in the low concentration regime measured at 0.1 and 0.25 M, far below the onset of glassy dynamics. This reduction in water activity could be significant in crowded biological systems, contributing to global change in protein energy landscape, resulting in a significant enhancement of protein stability under environmental stress. We observed similar dynamic reduction for two disaccharide osmolytes, sucrose and trehalose, with trehalose being the more effective in reducing solvation dynamics.
authors.affiliation: Department of Physics, Wesleyan University , Middletown, Connecticut 06457, United States.
authors.forename: Nimesh
authors.initials: N
authors.lastname: Shukla
authors.affiliation: Laboratoire de Spectroscopie Ultrarapide (LSU) and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, ISIC, FSB , CH-1015 Lausanne, Switzerland.
authors.forename: Enrico
authors.initials: E
authors.lastname: Pomarico
authors.affiliation: Department of Physics, Wesleyan University , Middletown, Connecticut 06457, United States.
authors.forename: Lee
authors.initials: L
authors.lastname: Chen
authors.affiliation: Laboratoire de Spectroscopie Ultrarapide (LSU) and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, ISIC, FSB , CH-1015 Lausanne, Switzerland.
authors.forename: Majed
authors.initials: M
authors.lastname: Chergui
authors.affiliation: Department of Physics, Wesleyan University , Middletown, Connecticut 06457, United States.|Molecular Biophysics Program, Wesleyan University , Middletown, Connecticut 06457, United States.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Othon
mesh_terms: D004187:Disaccharides / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D006860:Hydrogen Bonding; D015394:Molecular Structure; D009994:Osmolar Concentration; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D004187:Disaccharides; D005456:Fluorescent Dyes; D012997:Solvents; D014867:Water