The behavior of reorientational correlation functions of water at the water-lipid bilayer interface

Bhide, Shreyas Y.; Berkowitz, Max L.

doi:10.1063/1.2337623

Cited by 41 publications

(49 citation statements)

References 23 publications

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“…Some properties of biological membranes can be directly attributed to the characteristics of single phospholipid molecules. Due to their important role, phospholipids are the subject of numerous experimental and computational studies in recent decades [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Hybrid QM/MM simulation of the hydration phenomena of dipalmitoylphosphatidylcholine headgroup

Yin

Zhao

2009

Journal of Colloid and Interface Science

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The polar headgroup of dipalmitoylphosphatidylcholine (DPPC) molecule both in gas phase and aqueous solution is investigated by the hybrid quantum mechanical/molecular mechanical (QM/MM) method, in which the polar head of DPPC molecule and the bound water molecules are treated with density functional theory (DFT), while the apolar hydrocarbon chain of DPPC molecule is treated with MM method. It is demonstrated that the hybrid QM/MM method is both accurate and efficient to describe the conformations of DPPC headgroup. Folded structures of headgroup are found in gas phase calculations. In this work, both monohydration and polyhydration phenomena are investigated. In monohydration, different water association sites are studied. Both the hydration energy and the quantum properties of DPPC and water molecules are calculated at the DFT level of theory after geometry optimization. The binding force of monohydration is estimated by using the scan method. In polyhydration, more extended conformations are found and hydration energies in different polyhydration styles are estimated.

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Section: Introductionmentioning

confidence: 99%

Hybrid QM/MM simulation of the hydration phenomena of dipalmitoylphosphatidylcholine headgroup

Yin

Zhao

2009

Journal of Colloid and Interface Science

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“…Molecular dynamics (MD) simulations have studied hydration water extensively, concluding that most of the perturbation induced by an interface extends only a few molecular layers 1–4. In an experiment, it is often difficult to separate the contribution of the interfacial water from the overwhelming background of bulk water.…”

Section: Introductionmentioning

confidence: 99%

Water Dynamics at the Interface in AOT Reverse Micelles

et al. 2009

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The orientational dynamics of water molecules at the interface in large Aerosol-OT (AOT) reverse micelles are investigated using ultrafast infrared spectroscopy of the OD stretch of dilute HOD in H2O. In large reverse micelles(~9 nm diameter or larger), a significant amount of the nanoscopic water is sufficiently distant from the interface that it displays bulk-like characteristics. However, some water molecules interact with the interface and have vibrational absorption spectra and dynamics distinct from bulk water. The different characteristics of these interfacial waters allow their contribution to the data to be separated from the bulk. The infrared absorption spectrum of the OD stretch is analyzed to show that the interfacial water molecules have a spectrum that peaks near 2565 cm−1 in contrast to 2509 cm−1 in bulk water. A two component model is developed that simultaneously describes the population relaxation and orientational dynamics of the OD stretch in the spectral region of the interfacial water. The model provides a consistent description of both observables and demonstrates that water interacting with the interface has slower vibrational relaxation and orientational dynamics. The orientational relaxation of interfacial water molecules occurs in 18 ± 3 ps in contrast to the bulk water value of 2.6 ps.

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“…The diameter of the water nanopool is 9 nm. Experimental and theoretical results have shown that only the first hydration layer around an interface or solute is substantially perturbed (20,(24)(25)(26)(27), so we can assume that the interfacial water is located primarily within a shell having a thickness of 0.28 nm (3), which is the approximate diameter of a water molecule. Calculating the volume of this shell and dividing it by the total volume of the micelle interior yields a fraction of 0.18.…”

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confidence: 99%

Water dynamics at neutral and ionic interfaces

Fenn

Wong

Fayer

2009

Proc. Natl. Acad. Sci. U.S.A.

139

194

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The orientational dynamics of water at a neutral surfactant reverse micelle interface are measured with ultrafast infrared spectroscopy of the hydroxyl stretch, and the results are compared to orientational relaxation of water interacting with an ionic interface. The comparison provides insights into the influence of a neutral vs. ionic interface on hydrogen bond dynamics. Measurements are made and analyzed for large nonionic surfactant Igepal CO-520re-verse micelles (water nanopool with a 9-nm diameter). The results are compared with those from a previous study of reverse micelles of the same size formed with the ionic surfactant Aerosol-OT (AOT). The results demonstrate that the orientational relaxation times for interfacial water molecules in the two types of reverse micelles are very similar (13 ps for Igepal and 18 ps for AOT) and are significantly slower than that of bulk water (2.6 ps). The comparison of water orientational relaxation at neutral and ionic interfaces shows that the presence of an interface plays the dominant role in determining the hydrogen bond dynamics, whereas the chemical nature of the interface plays a secondary role.reverse micelles ͉ ultrafast IR experiments ͉ interfacial water ͉ hydrogen bond dynamics W ater molecules at interfaces are involved in many processes. In biology, water is found in crowded environments, such as cells, where it hydrates membranes and large biomolecules. In geology, interfacial water molecules can control ion adsorption and mineral dissolution. Embedded water molecules can change the structure of zeolites. In chemistry, water plays an important role as a polar solvent often in contact with interfaces, for example, in ion exchange resin systems.When water interacts with an interface, its hydrogen bonding properties are distinct from those of bulk water. Interactions with an interface influence water's ability to undergo hydrogen bond network rearrangements, which is a concerted process that involves a water molecule and its two water solvation shells (1, 2). For a water molecule to switch hydrogen bonding partners, other waters must also break and form new hydrogen bonds (1, 2). Such hydrogen bond rearrangements are necessary for both orientational and translational motions. An interface eliminates many of the pathways for hydrogen bond rearrangement that are available in bulk water. A fundamental question is whether the composition of or solely the presence of an interface plays the dominant role in affecting the hydrogen bond dynamics of interfacial water.Ultrafast infrared (IR) spectroscopy is a valuable technique for probing the dynamics of both bulk water and water at interfaces using the hydroxyl stretching mode of water as a reporter (3-17). Because processes in water involving hydrogen bond rearrangements occur on the picosecond time scale, the femtosecond time resolution of the IR techniques makes it possible to resolve the motions of water molecules on the time scale on which they are occurring. Examples of confined or restricted environments that...

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The behavior of reorientational correlation functions of water at the water-lipid bilayer interface

Cited by 41 publications

References 23 publications

Hybrid QM/MM simulation of the hydration phenomena of dipalmitoylphosphatidylcholine headgroup

Hybrid QM/MM simulation of the hydration phenomena of dipalmitoylphosphatidylcholine headgroup

Water Dynamics at the Interface in AOT Reverse Micelles

Water dynamics at neutral and ionic interfaces

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