scholarly journals Brillouin Neutron Spectroscopy as a Probe to Investigate Collective Density Fluctuations in Biomolecules Hydration Water

2012 ◽  
Vol 27 ◽  
pp. 293-305 ◽  
Author(s):  
D. Russo ◽  
A. Orecchini ◽  
A. De Francesco ◽  
F. Formisano ◽  
A. Laloni ◽  
...  
Keyword(s):  
Diffusion Processes ◽  
Terahertz Spectroscopy ◽  
Bulk Water ◽  
Density Fluctuations ◽  
Water Molecules ◽  
Relaxation Processes ◽  
Hydration Water ◽  
Solvent Interaction ◽  
Biological Functionality

The role of water in the behaviour of biomolecules is well recognized. The coupling of motions between water and biomolecules has been studied in a wide time scale for theselfpart whilecollectivedynamics is still quite unexplored.Self-dynamics provides information about the diffusion processes of water molecules and relaxation processes of the protein structure.Collectivedensity fluctuations might provide important insight on the transmission of information possibly correlated to biological functionality. The idea that hydration water layers surrounding a biological molecule show aself-dynamical signature that differs appreciably from that of bulk water, in analogy with glass-former systems, is quite accepted. In the same picture Brillouin terahertz spectroscopy has been used to directly probecollectivedynamics of hydration water molecules around biosystems, showing a weaker coupling and a more bulklike behaviour. We will discuss results of collective modes of hydration water, arising from neutron Brillouin spectroscopy, in the context of biomolecules-solvent interaction.

scholarly journals Ein Wasserstoffisotopieeffekt im CuSO4 * 5H2O

1969 ◽  
Vol 24 (10) ◽  
pp. 1502-1511
Author(s):  
Karl Heinzinger
Keyword(s):  
Water Vapor ◽  
Aqueous Solutions ◽  
Separation Factor ◽  
Room Temperature ◽  
Copper Ion ◽  
Hydrogen Isotopes ◽  
Bulk Water ◽  
Water Molecules ◽  
Hydration Water ◽  
Sulfate Solutions

Abstract There are two kinds of water in CuSO4·5H2O differing by their binding in the crystal. The oxygen of four water molecules is bonded to the copper ion, that of the fifth molecule is hydrogen bonded. It is shown that the D/H ratios of these two kinds of water differ by 5.7%, the light isotope being enriched in the water molecules coordinated with the copper ion. The results show that there is no exchange of the hydrogen isotopes during the time needed for dehydration at room temperature which takes several days. The assumption has been confirmed that the water coordinated with the copper ion leaves the crystal first on dehydration at temperatures below 50 °C. Additional measurements of the separation factor for the hydrogen isotopes between water vapor and copper sulfate solutions allow conclusions on the fractionation of the hydrogen isotopes between bulk water and hydration water in aqueous solutions.

scholarly journals Thrombin-thrombomodulin interaction: energetics and potential role of water as an allosteric effector

1995 ◽  
Vol 310 (1) ◽  
pp. 49-53 ◽  
Author(s):  
R De Cristofaro ◽  
M Picozzi ◽  
E De Candia ◽  
B Rocca ◽  
R Landolfi
Keyword(s):  
Conformational Changes ◽  
Potential Role ◽  
Competitive Inhibition ◽  
Entropy Change ◽  
Bulk Water ◽  
Water Molecules ◽  
Rabbit Lung ◽  
Allosteric Effector ◽  
Free Energy Of Binding

The interaction of rabbit lung thrombomodulin (TM) and C-terminal hirudin 54-65 fragment (Hir54-65) with human alpha-thrombin were investigated by exploiting their competitive inhibition of thrombin-fibrinogen interaction. Measurements of Ki values for TM and Hir54-65 interactions with human alpha-thrombin performed over a temperature range spanning from 10 to 40 degrees C showed a constant enthalpy for both ligands. The enthalpic and entropic contributions to the free energy of binding, however, are different for TM and the hirudin peptide. The calculated values of delta H and delta S, in fact, were -47.3 +/- 2.51 kJ (-11.3 +/- 0.6 kcal)/mol and -42.7 +/- 7.9 J (-10.2 +/- 1.9 cal)/mol.K for the hirudin peptide, while being -22.9 +/- 2.09 kJ (-5.47 +/- 0.5 kcal)/mol and 102.50 +/- 6.69 J (24.5 +/- 1.6 cal)/mol.K respectively for TM binding. These findings indicate that the interaction between thrombin and Hir54-65 is largely driven by the enthalpic contribution, whereas the positive entropy change is the driving force for the formation of the thrombin-TM complex. In other experiments performed in the presence of various concentrations of either sorbitol or sucrose it could be demonstrated that the value of the equilibrium association constant for thrombin-TM interaction increases as a function of the osmotic pressure, while the thrombin-Hir54-65 interaction was not affected by the same conditions. Moreover, control experiments showed that no major conformational changes are produced on TM by osmotic pressures used in the present study. From these experiments it was calculated that roughly 35 water molecules are released into the bulk water upon TM binding. Such a phenomenon, which is likely to be responsible for the entropic change described above, indicates the relevance of hydration processes for the formation of the thrombin-TM adduct.

Molecular Dynamics Study of a KCl Aqueous Solution: Dynamical Results

1987 ◽  
Vol 42 (3) ◽  
pp. 227-230 ◽  
Author(s):  
M. Migliore ◽  
S. L. Fornili ◽  
E. Spohr ◽  
K. Heinzinger
Keyword(s):  
Diffusion Coefficients ◽  
Md Simulation ◽  
Bulk Water ◽  
Water Molecules ◽  
Hydration Water ◽  
Self Diffusion ◽  
Average Temperature ◽  
Velocity Autocorrelation ◽  
Dynamical Properties ◽  
Velocity Autocorrelation Functions

In this paper we report on dynamical properties of a 2.2 molal aqueous KCl solution as obtained from an 8.7 ps MD simulation at an average temperature of 289 K. Velocity autocorrelation functions, self-diffusion coefficients and spectral densities of the hindered translational and librational motions of the ions and the water molecules assigned to three subsystems - hydration water of the cations, hydration water of the anions and bulk water - are discussed.

scholarly journals Structure, dynamics and reactions of protein hydration water

2004 ◽  
Vol 359 (1448) ◽  
pp. 1181-1190 ◽  
Author(s):  
Jeremy C. Smith ◽  
Franci Merzel ◽  
Ana-Nicoleta Bondar ◽  
Alexander Tournier ◽  
Stefan Fischer
Keyword(s):  
Water Molecule ◽  
Transfer Reactions ◽  
Protein Hydration ◽  
Water Molecules ◽  
Hydration Water ◽  
Protein Motions ◽  
Wide Range ◽  
Recent Computer ◽  
Proton Transfer Reactions

The apparent simplicity of the water molecule belies the wide range of fascinating protein phenomena in which it participates. We review recent computer simulation work on buried, internal water molecules, discussing the thermodynamics of water molecule binding and the participation of water in proton transfer reactions. Surface water molecules are also considered, with emphasis on the modification of average solvent structure on a protein surface, the role of water in the protein dynamical ‘glass’ transition and a simplified description of the protein motions thereby activated.

scholarly journals Cs Retention and Diffusion in C-S-H at Different Ca/Si Ratios

2018 ◽  
Author(s):  
Eduardo Duque-Redondo ◽  
Kazuo Yamada ◽  
Iñigo López-Arbeloa ◽  
Hegoi Manzano
Keyword(s):  
Diffusion Coefficients ◽  
Alkaline Earth ◽  
Diffusion Processes ◽  
Hydration Product ◽  
Cement Matrix ◽  
Water Molecules ◽  
Average Diffusion ◽  
Dynamics Simulations ◽  
And Diffusion

<div>Cement and concrete have been widely used as a barrier to isolate many types of contaminants, including radioactive waste, in repository sites. Nevertheless, the intrusion of groundwater in those nuclear repositories may release those contaminants by leaching mechanisms. Because of this, the retention and diffusion processes in cement matrix require to be analyzed in depth. The adsorption in cement and C‐S-H gel, its main hydration product, is influenced by factors as the pH, the composition or the alkali and alkaline earth content. In this work, molecular dynamics simulations were employed to study the role of Ca/Si ratio of the C‐S‐H in the capacity to retain Cs and diffusivity of these ions in gel pores. For that purpose, we built four different C‐S‐H models with Ca/Si ratios from 1.1 to 2.0. The results indicate better cationic retention at low Ca/Si ratios due to the interaction of the cations with the bridging silicate tetrahedrons. However, the average diffusion coefficients of the cations decrease at higher Ca/Si ratios because the high ionic constraint in the nanopore that induces a longrange ordering of the water molecules.</div>

scholarly journals Cs Retention and Diffusion in C-S-H at Different Ca/Si Ratios

2018 ◽  
Author(s):  
Eduardo Duque-Redondo ◽  
Kazuo Yamada ◽  
Iñigo López-Arbeloa ◽  
Hegoi Manzano
Keyword(s):  
Diffusion Coefficients ◽  
Alkaline Earth ◽  
Diffusion Processes ◽  
Hydration Product ◽  
Cement Matrix ◽  
Water Molecules ◽  
Average Diffusion ◽  
Dynamics Simulations ◽  
And Diffusion

<div>Cement and concrete have been widely used as a barrier to isolate many types of contaminants, including radioactive waste, in repository sites. Nevertheless, the intrusion of groundwater in those nuclear repositories may release those contaminants by leaching mechanisms. Because of this, the retention and diffusion processes in cement matrix require to be analyzed in depth. The adsorption in cement and C‐S-H gel, its main hydration product, is influenced by factors as the pH, the composition or the alkali and alkaline earth content. In this work, molecular dynamics simulations were employed to study the role of Ca/Si ratio of the C‐S‐H in the capacity to retain Cs and diffusivity of these ions in gel pores. For that purpose, we built four different C‐S‐H models with Ca/Si ratios from 1.1 to 2.0. The results indicate better cationic retention at low Ca/Si ratios due to the interaction of the cations with the bridging silicate tetrahedrons. However, the average diffusion coefficients of the cations decrease at higher Ca/Si ratios because the high ionic constraint in the nanopore that induces a longrange ordering of the water molecules.</div>

scholarly journals Local Dynamics of the Hydration Water and Poly(Methyl Methacrylate) Chains in PMMA Networks

2021 ◽  
Vol 9 ◽  
Author(s):  
Yoshihisa Fujii ◽  
Taiki Tominaga ◽  
Daiki Murakami ◽  
Masaru Tanaka ◽  
Hideki Seto
Keyword(s):  
Methyl Methacrylate ◽  
Bulk Water ◽  
Polymer Chains ◽  
Water Molecules ◽  
Hydration Water ◽  
Segmental Motion ◽  
Local Motion ◽  
Deuterium Labeling ◽  
Elastic Neutron ◽  
Poly Methyl Methacrylate

The dynamic behavior of water molecules and polymer chains in a hydrated poly(methyl methacrylate) (PMMA) matrix containing a small amount of water molecules was investigated. Water molecules have been widely recognized as plasticizers for activating the segmental motion of polymer chains owing to their ability to reduce the glass transition temperature. In this study, combined with judicious hydrogen/deuterium labeling, we conducted quasi-elastic neutron scattering (QENS) experiments on PMMA for its dry and hydrated states. Our results clearly indicate that the dynamics of hydrated polymer chains are accelerated, and that individual water molecules are slower than bulk water. It is therefore suggested that the hydration water affects the local motion of PMMA and activates the local relaxation process known as restricted rotation, which is widely accepted to be generally insensitive to changes in the microenvironment.

Effect of cluster-gradient architecture of nanostructured topocomposites on features of tribointeraction with heterophased material

2020 ◽  
pp. 130-135
Author(s):  
D.N. Korotaev ◽  
K.N. Poleshchenko ◽  
E.N. Eremin ◽  
E.E. Tarasov
Keyword(s):  
Wear Resistance ◽  
Titanium Alloy ◽  
Energy Dissipation ◽  
Phase Structure ◽  
Diffusion Processes ◽  
Structural Phase ◽  
High Wear Resistance ◽  
Wear Characteristics ◽  
And Diffusion

The wear resistance and wear characteristics of cluster-gradient architecture (CGA) nanostructured topocomposites are studied. The specifics of tribocontact interaction under microcutting conditions is considered. The reasons for retention of high wear resistance of this class of nanostructured topocomposites are studied. The mechanisms of energy dissipation from the tribocontact zone, due to the nanogeometry and the structural-phase structure of CGA topocomposites are analyzed. The role of triboactivated deformation and diffusion processes in providing increased wear resistance of carbide-based topocomposites is shown. They are tested under the conditions of blade processing of heat-resistant titanium alloy.

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