Simulations of Zwitterionic and Anionic Phospholipid Monolayers

Kaznessis, Yiannis N.; Kim, Sangtae; Larson, Ronald G.

doi:10.1016/s0006-3495(02)75525-2

Cited by 101 publications

(139 citation statements)

References 55 publications

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“…More recent fully atomistic MD results 6 are not any closer to reproducing experimental data. The area per lipid is 15%-20% too large in the CG model, which contributes to the offset compared to the experimental curve (see Figure 5).…”

Section: Resultsmentioning

confidence: 75%

Molecular Dynamics Investigations of Lipid Langmuir Monolayers Using a Coarse-Grain Model

et al. 2003

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We present the results of molecular dynamics (MD) simulations of coarse-grain 1,2-di-n-alkanoyl-sn-glycero-3-phosphocholine Langmuir monolayer systems. Two separate alkanoyl length lipids are considered. Surface pressure versus area per lipid isotherms are obtained for both lipid species and are compared to experimental and previous atomistic MD work. The short-tail lipid cannot support a surface pressure above that expected at the critical micelle concentration. In contrast, the long-tail lipid is studied in the metastable regime of slightly negative surface tension. At still higher surface coverage, the interface is destabilized, leading to monolayer collapse via a novel mechanism in which a charge-neutralizing bridge of zwitterionic headgroups is established to transport lipids across the alkanoyl region. Area per lipid compression simulations are also performed at constant lipid number to demonstrate that the observed instabilities are generic.

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Section: Resultsmentioning

confidence: 75%

Molecular Dynamics Investigations of Lipid Langmuir Monolayers Using a Coarse-Grain Model

et al. 2003

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“…The number of water molecules that diffuse from the bottom water phase to the top of the simulation cell on account of periodic boundary conditions was found to be negligible. Other researchers have used a wallpotential to prevent diffusion of the water molecules away from the water phase [17,30]. However, this approach involves the computationally expensive external force calculation for a water molecule based on its position during the simulation with NAMD and was found to be unnecessary.…”

Section: Methodsmentioning

confidence: 99%

“…In order to study the behaviour of the components of pulmonary surfactant at the air/water interface, Kaznessis et al have simulated DPPC and DPPG monolayers in the canonical (constant NVT) ensemble at various surface densities [17]. They have presented the effects of surface density and the presence of calcium ions in the sub-phase on the thickness of the monolayer in terms of specific interactions between groups in the two phospholipids.…”

Section: Pulmonary Surfactant Functionalitymentioning

confidence: 99%

Equation of state for a coarse-grained DPPC monolayer at the air/water interface

Adhangale

Gaver

2006

Molecular Physics

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Pulmonary surfactant, a complex mixture of phospholipids and proteins, secreted by the type II epithelial cells in the lungs, is crucial to reducing the effort required for breathing. A lack of adequate amounts of pulmonary surfactant in underdeveloped lungs of premature infants results in infant respiratory distress syndrome (RDS). Surfactant replacement therapy (SRT) is the approved method of mitigating the effects of RDS. The development of new SRT regimens requires a fundamental understanding of the links between surfactant biochemistry and functionality. We use a coarse-grained (CG) model to predict the surface pressure-surface concentration relationship (equation of state) for pure DPPC, which is a major component of endogenous and synthetic pulmonary surfactant mixtures. We show that the model can be efficiently used to predict the equation of state in excellent agreement with experimental results. We also study the structure of the monolayer as a function of the surface tension of the system. We show that a decrease in the applied surface tension results in an increase in order in the head group region and a decrease in order in the tail region of DPPC. This technique may be useful in the prediction of equations of state for surfactant replacements.

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“…17 In simulations by Tomassone et al using a coarsegrained model of soluble surfactants the G-LE coexistence region at low area densities was reproduced. 18 In more recent work monolayers comprising DPPC mixed with an anionic lipid 19 as well as monolayers containing a human surfactant protein 20 were simulated to study pulmonary surfactantassociated phenomena. The coexistence of multiple lipid phases, however, which is essential for determining the phase diagram of phospholipid monolayers, has to our knowledge not previously been studied using atomistic simulations.…”

Section: Introductionmentioning

confidence: 99%

Simulation studies of pore and domain formation in a phospholipid monolayer

Knecht

Müller

Bonn

et al. 2004

The Journal of Chemical Physics

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Simulation studies of pore and domain formation in a phospholipid monolayer.Knecht, V.; Müller, M.; Bonn, M.; Marrink, S.J.; Mark, A.E. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Despite extensive study the phase behavior of phospholipid monolayers at an air-water interface is still not fully understood. In particular recent vibrational sum-frequency generation ͑VSFG͒ spectra of DPPC monolayers as a function of area density show a sharp transition in the order of the lipid chains at 1.10 nm 2 /molecule. This is in a region where the lateral pressure as a function of area is effectively constant. We have investigated the nature of this transition by studying the phase behavior of DPPC monolayers as a function of area density using molecular-dynamics simulations. The changes in order within the monolayer as a function of area density correlate well with the experimental signal. At 0.58 nm 2 /molecule we observe the onset of lateral separation of highly ordered and disordered lipids, indicating the coexistence of a gel-like liquid condensed and a fluidlike liquid expanded phase. At 0.97 nm 2 /molecule the monolayer ruptures, marking the onset of the liquid-gas ͑G͒ coexistence region. This is much earlier than suggested by fluorescence microscopy results and implies that at the point of rupture, the initial pores have an equilibrium size smaller than ϳ500 nm in diameter. The rupture of the monolayer leads to a sharp increase in the overall lipid order that explains the sharp transition observed in the VSFG measurements. VSFG measurements thus may represent a sensitive means to determine the onset of the liquid-gas ͑G͒ coexistence region for such systems.

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Simulations of Zwitterionic and Anionic Phospholipid Monolayers

Cited by 101 publications

References 55 publications

Molecular Dynamics Investigations of Lipid Langmuir Monolayers Using a Coarse-Grain Model

Molecular Dynamics Investigations of Lipid Langmuir Monolayers Using a Coarse-Grain Model

Equation of state for a coarse-grained DPPC monolayer at the air/water interface

Simulation studies of pore and domain formation in a phospholipid monolayer

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