Molecular Dynamics Simulation of Water between Two Charged Layers of Dipalmitoylphosphatidylserine

Cascales, J.J. López; Berendsen, Herman J. C.; delaTorre, J.G.

doi:10.1021/jp9516405

Cited by 47 publications

(34 citation statements)

References 26 publications

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“…A scheme of the benzocaine molecule used in this work is shown in Figure 1. The force field parameters and electrostatic charge distribution of the DPPC and DPPS were the same as those used by Egberts et al 27 and Cascales et al 28 in previous simulations of pure bilayers of DPPC and DPPS in their liquid crystalline state. The charge distribution and force field parameters for benzocaine were taken from a previous article.…”

Section: A Setting Up the Simulation Conditionsmentioning

confidence: 99%

Thermodynamic study of benzocaine insertion into different lipid bilayers

Cascales

Costa

Porasso

2011

The Journal of Chemical Physics

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Despite the general consensus concerning the role played by sodium channels in the molecular mechanism of local anesthetics, the potency of anaesthetic drugs also seems to be related with their solubility in lipid bilayers. In this respect, this work represents a thermodynamic study of benzocaine insertion into lipid bilayers of different compositions by means of molecular dynamics simulation. Thus, the free energy profiles associated with benzocaine insertion into symmetric lipid bilayers composed of different proportions of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylserine were studied. From the simulation results, a maximum in the free energy ( G) profile was measured in the region of the lipid/solution interface. This free energy barrier appears to be very much dependent on the lipid composition of the membrane. On the other hand, the minimum free energy ( G) within the bilayer remained almost independent of the lipid composition of the bilayer. By repeating the study at different temperatures, it was seen how the spontaneity of benzocaine insertion into the lipid bilayer is due to an increase in the entropy associated with the process.

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Section: A Setting Up the Simulation Conditionsmentioning

confidence: 99%

Thermodynamic study of benzocaine insertion into different lipid bilayers

Cascales

Costa

Porasso

2011

The Journal of Chemical Physics

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“…The reason for using this experimental value instead of the potential calculated from simulation is that the electrostatic potential calculated from simulation is overestimated, due to the net charge of the monolayer and the absence of polarizability in the models used in our simulations, as was previously reported for other charged systems. [33] Thus, the partition constant K of MB between aqueous solution and the DMPA monolayer can be estimated as Equation (2):…”

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confidence: 99%

Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

et al. 2010

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Adsorption of methylene blue (MB) onto a dimyristoylphosphatidic acid (DMPA) Langmuir air/water monolayer is studied by molecular dynamics (MD) simulations, UV reflection spectroscopy and surface potential measurements. The free-energy profile associated with MB transfer from water to the lipid monolayer shows two minima of -66 and -60 kJ mol(-1) for its solid and gas phase, respectively, corresponding to a spontaneous thermodynamic process. From the position of the free-energy minima, it is possible to predict the precise location of MB in the interior of the DMPA monolayer. Thus, MB is accommodated in the phosphoryl or carbonyl region of the DMPA Langmuir air/water interface, depending on the isomorphic state (solid or gas phase, respectively). Reorientation of MB, measured from the bulk solution to the interior of the lipid monolayer, passes from a random orientation in bulk solution to an orientation parallel to the surface of the lipid monolayer when MB is absorbed.

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“…The atomic charge distribution on each neutral polypyrrole molecule was calculated by mean of the CNDO quantum mechanical method. 28 However, during the simulations, all the charges were reduced by 2 ͑except for the water molecules͒ as in previous works, 18,22,23 to reduce the poor screening of the SPC model associated with the absence of polarizability in the model. This has been effective in simulations of other interfaces, such as biological membranes, micelles and soap/alcohol/water interfaces.…”

Section: Methods and Modelsmentioning

confidence: 99%

“…Thus, classical molecular dynamic simulations have been successfully employed in a vast number of fields such as proteins, 17 lipid layers, 18 ion transfer across immiscible liquid interfaces, 19,20 and liquid/solid interfaces. 21 Based on our previous work in the field of lipid/ water interfaces, [22][23][24][25] we carried out a molecular dynamic simulation of the polypyrrole/water interface in atomic detail in two different steady oxidation states of the system: reduced ͑noncharged͒ and oxidized ͑charged͒ state.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamic simulation of the hydration and diffusion of chloride ions from bulk water to polypyrrole matrix

Cascales

Otero

2004

The Journal of Chemical Physics

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A molecular dynamic simulation of wet polypyrrole film was carried out, in both oxidized and reduced state. The system was modeled by two layers of polypyrrole, water and chloride ions (as counterions required for charge balance in the oxidized state) in atomic detail to provide an insight into some dynamic and steady properties of the system. Our simulations pointed to a swelling of the polymer matrix after oxidation due to electrostatic repulsions between charged sites of the oxidized polypyrrole, followed by penetration of the polypyrrole by counterions to maintain the electroneutrality of the system. Associated with this penetration of counterions toward the core of the oxidized polypyrrole, dehydration of the counterions was observed. This dehydration was compensated (in part) by a strong coordination with the charged sites of the polymer. The remaining hydrophobicity inside the polymer also contributed to the dehydration of these counterions. The translational diffusion coefficient of chloride ions was also calculated at different positions of the polypyrrole/water interface, from bulk water to the inner polymer matrix. A value of 4.1 x 10(-5) cm(2) s(-1) was measured in the bulk water compared to 5 x 10(-7) cm(2) s(-1) inside the polymer, representing a diminution of two orders of magnitude for the translational diffusion coefficient from bulk water to the core of a oxidized polypyrrole matrix. These results were in good agreement with experimental data.

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Molecular Dynamics Simulation of Water between Two Charged Layers of Dipalmitoylphosphatidylserine

Cited by 47 publications

References 26 publications

Thermodynamic study of benzocaine insertion into different lipid bilayers

Thermodynamic study of benzocaine insertion into different lipid bilayers

Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

Molecular dynamic simulation of the hydration and diffusion of chloride ions from bulk water to polypyrrole matrix

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