Tetrahedral order in homologous disaccharide-water mixtures

Abstract

The present work aims at evidencing the "kosmotrope" nature of trehalose through the analysis of inelastic neutron scattering measurements on trehalose and sucrose water solutions at different temperatures. Neutron spectra were collected by using the spectrometer MARI at the ISIS pulsed neutron source of the Rutherford Appleton Laboratory (Chilton, UK). To study the structural modifications induced on the tetrahedral hydrogen-bond network of water by homologous disaccharides, as a first step, the vibrational properties of pure water at different temperatures have been investigated. In particular, the temperature behavior of the intramolecular OH stretching mode has been analyzed. Successively, the vibrational properties for pure water have been compared with those of the sugar water solutions focusing the attention on the tetrahedral network-forming tendency. Finally, the obtained findings have been compared with previous Raman scattering evidences, and the results interpreted in the frame of recent molecular dynamics simulation works.

Specific ion effects in polysaccharide dispersions

“…We argue that trehalose establishes crosslinking intra-and intermolecular interactions, resulting in a strengthening of the system. Indeed, trehalose is known as a kosmotrope or water-structure maker: this disaccharide is able to break the tetrahedral HB network of water and re-order the water molecules in the hydration layer (Branca et al, 2005;Lerbret et al, 2005). However, experiments conducted by us on a 0.5 M solution of trehalose in water show neither an increase in the viscosity, nor a modification in the rheological response.…”

Osmolyte-Induced Perturbations of Hydrogen Bonding between Hydration Layer Waters: Correlation with Protein Conformational Changes

“…(Here the reviewer 2 thought the following sentence is awkward??) A naturally occurring osmolyte remarkable protein stabilizing and cryoprotection properties, trehalose is found to be relatively highly hydrated 101,102 and have decreased hydration layer mobility 103 , lower compressibility 104 , lower diffusion coefficient 100 and decreased tetrahedrality of the surrounding water structure 105,106 . These properties are consistent with the low number of intramolecular hydrogen bonds and the larger flexibility of its glycosidic linkage 101 .…”

“…These properties are consistent with the low number of intramolecular hydrogen bonds and the larger flexibility of its glycosidic linkage 101 . These features allow trehalose to to strongly influence the surrounding waters and foster the formation of strong hydrogen bonding networks of water even with other sugars as sucrose 28,105–107 . These results suggest that the efficacy of a given sugar or polysaccharide to enhance protein stability is a function not only of the enhancement of hydrogen bonding within the bulk layer but also the ability of the osmolyte to integrate the hydration waters (or the protein surface) into the extended hydrogen bonding network.…”

Effect of trehalose on protein structure

“…66 Raman scattering experiments reveal the disruption of the tetrahedral network of water molecules on addition of trehalose. 9 This ''destructuring'' of the water network by trehalose and ordering the water molecules around itself (as a kosmotrope) does not allow the formation of ice and makes trehalose one of the best cryoprotectants known.…”