Diffusive Dynamics of Water in the Presence of Homologous Disaccharides: A Comparative Study by Quasi Elastic Neutron Scattering. IV (original) (raw)
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Study of the dynamical properties of water in disaccharide solutions
2007
This work presents quasi-elastic neutron scattering (QENS) and neutron spin echo (NSE) findings on homologous disaccharide (i.e. trehalose, maltose and sucrose)/water solutions as a function of temperature. The dynamical properties of these systems are investigated by QENS, which, on the picosecond scale, allows for the characterisation of the diffusion of both solutes and solvent. On the other hand, NSE investigates the dynamics on the nanosecond scale, allowing for the relaxation times of the disaccharide/ water systems to be evaluated. The experimental data highlight a strong slowing down of water in the presence of disaccharides. The whole set of findings indicates, therefore, a noticeable disaccharide-water interaction, which is more intense in the case of trehalose. This feature can justify its higher bioprotective effectiveness.
Neutron spectroscopy of hydrated disaccharides : Trehalose vs. sucrose
Le Journal de Physique IV, 2000
Neutron time-of-flight spectra for two hydrated &saccharides at 300 K show significant differences with respect to (i) discrete features in the 10 to 70 meV region, and (ii) a broad low-frequency band centred on 5.5-6 meV. We analysed these in terms of generalised frequency distributions. The peak as well as integrated intensities of (ii) between 0.2 and 10 meV differ markedly in their dependence on momentum transfer.
Chemical Physics, 2013
In the present paper the results of a wavevector and thermal analysis of Elastic Incoherent Neutron Scattering (EINS) data collected on water mixtures of three homologous disaccharides through a wavelet approach are reported. The wavelet analysis allows to compare both the spatial properties of the three systems in the wavevector range of Q = 0.27 Å À1 Ä 4.27 Å À1. It emerges that, differently from previous analyses, for trehalose the scalograms are constantly lower and sharper in respect to maltose and sucrose, giving rise to a global spectral density along the wavevector range markedly less extended. As far as the thermal analysis is concerned, the global scattered intensity profiles suggest a higher thermal restrain of trehalose in respect to the other two homologous disaccharides.
Bioprotectant Effectiveness of Homologous Disaccharides by Elastic Incoherent Neutron Scattering
European Chemical Bulletin, 2013
A new wavevector analysis performed by wavelet transform of Elastic Incoherent Neutron Scattering (EINS) data on three bioprotectant systems, i.e. on the homologous disaccharides trehalose, maltose and sucrose, is presented. The analysis allows to compare the spatial properties of the three systems in the wavevector range of , revealing the existence of different kinds of protons dynamics. It emerges that, differently from previous wavevector analyses, both the low and high wavevector contributions for trehalose, at all the investigated temperature values, are constantly lower and sharper, giving rise to a global energy distribution along the wavevector range markedly less extended. Furthermore an innovative model for the global EINS intensity temperature behavior is applied to put into evidence the higher thermal restrain for trehalose in respect to the other two homologous disaccharides. These findings give an account for the bioprotectant effectiveness of trehalose in the medical...
Slowing down of water dynamics in disaccharide aqueous solutions
Journal of Non-Crystalline Solids, 2011
The dynamics of water in aqueous solutions of three homologous disaccharides, namely trehalose, maltose and sucrose, has been analyzed by means of molecular dynamics simulations in the 0-66 wt % concentration range. The low-frequency vibrational densities of states (VDOS) of water were compared with the susceptibilities χ" of 0-40 wt % solutions of trehalose in D 2 O obtained from complementary Raman scattering experiments. Both reveal that sugars significantly stiffen the local environments experienced by water. Accordingly, its translational diffusion coefficient decreases when the sugar concentration increases, as a result of an increase of water-water hydrogen bonds lifetimes and of the corresponding activation energies. This induced slowing down of water dynamics, ascribed to the numerous hydrogen bonds that sugars form with water, is strongly amplified at concentrations above 40 wt % by the percolation of the hydrogen bond network of sugars, and may partially explain their well-known stabilizing effect on proteins in aqueous solutions.
Bio-protective effects of homologous disaccharides on biological macromolecules
2012
In this contribution the effects of the homologous disaccharides trehalose and sucrose on both water and hydrated lysozyme dynamics are considered by determining the mean square displacement (MSD) from elastic incoherent neutron scattering (EINS) experiments. The self-distribution function (SDF) procedure is applied to the data collected, by use of IN13 and IN10 spectrometers (Institute Laue Langevin, France), on trehalose and sucrose aqueous mixtures (at a concentration corresponding to 19 water molecules per disaccharide molecule), and on dry and hydrated (H 2 O and D 2 O) lysozyme also in the presence of the disaccharides. As a result, above the glass transition temperature of water, the MSD of the water-trehalose system is lower than that of the water-sucrose system. This result suggests that the hydrogen-bond network of the water-trehalose system is stronger than that of the watersucrose system. Furthermore, by taking into account instrumental resolution effects it was found that the system relaxation time of the water-trehalose system is longer than that of the water-sucrose system, and the system relaxation time of the protein in a hydrated environment in the presence of disaccharides increases sensitively. These results explain the higher bioprotectant effectiveness of trehalose. Finally, the partial MSDs of sucrose/water and trehalose/ water have been evaluated. It clearly emerges from the analysis that these are almost equivalent in the low-Q domain (0-1.7 Å-1) but differ substantially in the high-Q range (1.7-4 Å-1). These findings reveal that the lower structural sensitivity of trehalose to thermal changes is connected with the local spatial scale. Keywords Bioprotection Á Biological molecules Á Homologous disaccharides Á Lysozyme Á Water Á Elastic incoherent neutron scattering Special Issue: Biophysics of cosmetics.
Structure of Aqueous Trehalose Solution by Neutron Diffraction and Structural Modeling
Journal of Physical Chemistry B, 2016
The molecular structure of an aqueous solution of the disaccharide trehalose (C 12 H 22 O 11) has been studied by neutron diffraction and empirical potential structure refinement modeling. Six different isotope compositions with 33 wt % trehalose (corresponding to 38 water molecules per trehalose molecule) were measured to ensure that water− water, trehalose−water, and trehalose−trehalose correlations were accurately determined. In fact, this is the first neutron diffraction study of an aqueous trehalose solution in which also the nonexchangeable hydrogen atoms in trehalose are deuterated. With this approach, it was possible to determine that (1) there is a substantial hydrogen bonding between trehalose and water (∼11 hydrogen bonds per trehalose molecule), which is in contrast to previous neutron diffraction studies, and (2) there is no tendency of clustering of trehalose, in contrast to what is generally observed by molecular dynamics simulations and experimentally found for other disaccharides. Thus, the results give the structural picture that trehalose prefers to interact with water and participate in a hydrogen-bonded network. This strong network character of the solution might be one of the key reasons for its extraordinary stabilization effect on biological materials.
Dynamics of Water Molecules in Glucose Solutions
The Journal of Physical Chemistry B, 2004
The effects of the solution of glucose molecules on the dynamics of solvent water have been studied by quasielastic neutron scattering (QENS) measurements on solutions of selectively deuterated glucose in natural water. The data are fitted to two Lorentzians ascribed to pure translational and mixed translational and rotational character, respectively. The addition of the glucose to the water causes a substantial slowing down, by a factor 10 for the translational diffusion and 3-4 for the rotational motion at the highest concentration studied, 1:11 C 6 H 12 O 6 :H 2 O. The values obtained for water diffusion constants are consistent with previous QENS and NMR experiments on monosaccharide solutions but an order of magnitude higher than those derived from a recent molecular dynamics simulation.
Translational and Rotational Dynamics of Monosaccharide Solutions
Journal of Physical Chemistry B, 2009
Molecular dynamics computer simulations have been carried out on aqueous solutions of glucose at concentrations bracketing those previously measured with quasi-elastic neutron scattering (QENS), in order to investigate the motions and interactions of the sugar and water molecules. In addition, QENS measurements have been carried out on fructose solutions to determine whether the effects previously observed for glucose apply to monosaccharide solutions. The simulations indicate a dynamical analog between higher solute concentration and lower temperature that could provide a key explanation of the bioprotective phenomena observed in many living organisms. The experimental results on fructose solutions show qualitatively similar behavior to the glucose solutions. The dynamics of the water molecules are essentially the same, while the translational diffusion of the sugar molecules is slightly faster in the fructose solutions.
Journal of The Royal Society Interface, 2006
Neutron scattering has been demonstrated to be a powerful tool for characterizing the structure and dynamics of biological molecules and for investigating the physical and chemical mechanisms of biophysical processes. The aim of the present work is to investigate by inelastic neutron scattering (INS) the vibrational behaviour of a class of bioprotectant systems, such as homologous disaccharides, trehalose, maltose and sucrose, in water mixtures. INS measurements have been performed on trehalose/H 2 O, maltose/H 2 O and sucrose/H 2 O mixtures at very low temperature as a function of concentration by using the thermal original spectrometer with cylindrical analyzers (TOSCA) spectrometer at the ISIS Facility (DRAL, UK). The findings allow the analyses of the vibrational features of the INS spectra in order to study the effect of disaccharides on the H 2 O hydrogen-bonded tetrahedral network. The obtained neutron scattering findings point out that disaccharides, and in particular trehalose, have a destructuring effect on the water tetrahedral network, as emphasized by the analysis of the librational modes region from 50 to 130 meV energy transfer. On the other hand, the analysis of the bending modes region (130-225 meV) shows a locally ordered structure in the disaccharide/H 2 O mixtures. Finally, the observed experimental evidences are linked to the different bioprotective effectiveness of disaccharides as a function of concentration.