Journal ArticleDOI
Entropy and dynamics of water in hydration layers of a bilayer.
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The translational diffusion of water in the vicinity of the head groups is found to be in a subdiffusive regime and the rotational diffusion constant increases going away from the interface, supported by the slower reorientational relaxation of the dipole vector and OH bond vector of interfacial water.Abstract:
We compute the entropy and transport properties of water in the hydration layer of dipalmitoylphosphatidylcholine bilayer by using a recently developed theoretical scheme [two-phase thermodynamic model, termed as 2PT method; S.-T. Lin et al., J. Chem. Phys. 119, 11792 (2003)] based on the translational and rotational velocity autocorrelation functions and their power spectra. The weights of translational and rotational power spectra shift from higher to lower frequency as one goes from the bilayer interface to the bulk. Water molecules near the bilayer head groups have substantially lower entropy (48.36 J/mol/K) than water molecules in the intermediate region (51.36 J/mol/K), which have again lower entropy than the molecules (60.52 J/mol/K) in bulk. Thus, the entropic contribution to the free energy change (TΔS) of transferring an interface water molecule to the bulk is 3.65 kJ/mol and of transferring intermediate water to the bulk is 2.75 kJ/mol at 300 K, which is to be compared with 6.03 kJ/mol for melting of ice at 273 K. The translational diffusion of water in the vicinity of the head groups is found to be in a subdiffusive regime and the rotational diffusion constant increases going away from the interface. This behavior is supported by the slower reorientational relaxation of the dipole vector and OH bond vector of interfacial water. The ratio of reorientational relaxation time for Legendre polynomials of order 1 and 2 is approximately 2 for interface, intermediate, and bulk water, indicating the presence of jump dynamics in these water molecules.read more
Citations
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References
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Journal ArticleDOI
The dynamics of water at the phospholipid bilayer surface: a molecular dynamics simulation study
TL;DR: In this article, the effect of the membrane on the dynamics of water was investigated in a fully hydrated 1-palmitoyl 2-oleoyl-phosphatidylcholine (POPC) bilayer.
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Orientational dynamics of water in phospholipid bilayers with different hydration levels.
Zhancheng Zhang,Max L. Berkowitz +1 more
TL;DR: In this paper, the orientational dynamics of water next to bilayers containing dilauroyl phosphatidylcholine (DLPC) phospholipids with different hydration levels were studied.
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Estimating the entropy of liquids from atom–atom radial distribution functions: silica, beryllium fluoride and water
TL;DR: In this paper, the pair correlation entropy is demonstrated to be sufficiently accurate that the density-temperature regime of anomalous behaviour as well as the strength of the entropy anomaly can be predicted reliably for both ionic melts and different rigid-body pair potentials for water.
Journal ArticleDOI
Reinterpretation of the Liquid Water Quasi-Elastic Neutron Scattering Spectra Based on a Nondiffusive Jump Reorientation Mechanism
TL;DR: This reinterpretation provides the first experimental confirmation that water reorientation is not a diffusive process, and occurs through large angular jumps.
Journal ArticleDOI
Estimating Entropy of Liquids from Atom-Atom Radial Distribution Functions: Silica, Beryllium Fluoride and Water
TL;DR: In this article, the pair correlation entropy is used to estimate the entropy of ionic and molecular liquids from atom-atom radial distribution function data, and it is shown that the pair-correlation entropy is sufficiently accurate that the density-temperature regime of anomalous behaviour as well as the strength of the entropy anomaly can be predicted reliably.