Hydrogen Bonding Structure and Dynamics of Water at the Dimyristoylphosphatidylcholine Lipid Bilayer Surface from a Molecular Dynamics Simulation

López, Carlos F.; Nielsen, Steven O.; Klein, Michael L.; Moore, Preston B.

doi:10.1021/jp037618q

Cited by 161 publications

(232 citation statements)

References 63 publications

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“…94 On the other hand, sodium ions are known to associate with the carbonyl groups of glycerophospholipids, 115 often forming complexes with two or more lipid molecules, as suggested by several recent MD simulations of bilayer membranes. [103][104][105][106][107][108][109][110][111][112][113] We will see later (and especially in the companion paper) that the sodium-lipid association must in fact be invoked to explain the results obtained using subphase electrolytes with more kosmotropic anions, such as NaF. This association is also responsible for a sizable reduction of the area per molecule in bilayers, as reported by simulations.…”

Section: Mathematical Description Of Modelsmentioning

confidence: 89%

Liquid Expanded Monolayers of Lipids As Model Systems to Understand the Anionic Hofmeister Series: 1. A Tale of Models

2009

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In this work, we use Langmuir monolayers of dipalmitoyl phosphatidylcholine (DPPC) as model systems to enhance the understanding of specific anion effects in physicochemical and biological systems. The 298 K isotherms (equation of state, EOS) of DPPC over solutions of a range of sodium salts depend strongly on the type and concentration of the salt in the subphase. We focus in particular on the liquid expanded phase region of the DPPC EOS and assume that the deviation of the isotherms over electrolyte solutions from that over pure water is due entirely to the charging of the lipid monolayer by the ions. We then examine the ability of a range of phenomenological continuum models to explain the pressure increase in the presence of electrolytes. The important finding is that insoluble lipid monolayers allow the discrimination between possible modes of ion-lipid interaction. Chemical binding models, simple or modified, cannot fit the range of data presented in this work. Both dispersion interaction and partitioning models fit most of the experimental isotherms and provide unique values for dispersion coefficients or ionic partitioning constants, respectively, even though the nature of these models is completely different (the former concentrates on the potential of mean force that acts on an ion in the double layer, while the latter concentrates on the treatment of interactions at the interface). Surprisingly, the respective fitting parameters are very highly correlated, reflecting, we believe, the effect of ion size on ionic properties and interactions. With sodium fluoride (NaF) as the subphase electrolyte, it is demonstrated that sodium exhibits a weak complexation-type interaction with the zwitterionic lipids. The simple dispersion and partitioning models cannot account for the NaF results, highlighting the need for more complex salt-lipid interaction models that account both for sodium binding and anion partitioning. This realization sets the stage for the companion paper.

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Section: Mathematical Description Of Modelsmentioning

confidence: 89%

Liquid Expanded Monolayers of Lipids As Model Systems to Understand the Anionic Hofmeister Series: 1. A Tale of Models

2009

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“…The simulations also reveal an enhancement in the van der Waals interactions from -27 k B T to -33 k B T per hydrocarbon tail when the tail length n increases from 14 to 16, which suggests a gain of ∼2 k B T per hydrocarbon atom in the crystalline membrane structure (17). The hydration of lipid bilayers has been studied previously by MD simulations in systems with charged groups such as dimyristoylphosphatidylcholine (DMPC) lipid bilayers (37), which showed that the average number of hydrogen bonds per lipid oxygen atom varies depending on its position within the lipid. Specifically, the oxygen atoms of the phosphate group in contact with water were found to have a higher probability to form hydrogen bonds compared with the ester oxygen atoms.…”

Section: Resultsmentioning

confidence: 79%

Crystalline polymorphism induced by charge regulation in ionic membranes

Leung

Palmer

Kewalramani

et al. 2013

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

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The crystallization of molecules with polar and hydrophobic groups, such as ionic amphiphiles and proteins, is of paramount importance in biology and biotechnology. By coassembling dilysine (+2) and carboxylate (-1) amphiphiles of various tail lengths into bilayer membranes at different pH values, we show that the 2D crystallization process in amphiphile membranes can be controlled by modifying the competition of long-range and shortrange interactions among the polar and the hydrophobic groups. The pH and the hydrophobic tail length modify the intermolecular packing and the symmetry of their crystalline phase. For hydrophobic tail lengths of 14 carbons (C 14 ), we observe the coassembly into crystalline bilayers with hexagonal molecular ordering via in situ small-and wide-angle X-ray scattering. As the tail length increases, the hexagonal lattice spacing decreases due to an increase in van der Waals interactions, as demonstrated by atomistic molecular dynamics simulations. For C 16 and C 18 we observe a reentrant crystalline phase transition sequence, hexagonalrectangular-C-rectangular-P-rectangular-C-hexagonal, as the solution pH is increased from 3 to 10.5. The stability of the rectangular phases, which maximize tail packing, increases with increasing tail length. As a result, for very long tails (C 22 ), the possibility of observing packing symmetries other than rectangular-C phases diminishes. Our work demonstrates that it is possible to systematically exchange chemical and mechanical energy by changing the solution pH value within a range of physiological conditions at room temperature in bilayers of molecules with ionizable groups.amphiphilic membranes | self-assembly | hydrophobic interaction N ature uses electrostatic interactions among positively and negatively charged groups to induce the organization of biomolecules into highly complex structures that respond to ionic changes (1, 2). The structure of the aggregates at specific ionic conditions is intimately related to its function. Therefore, understanding the mechanisms that control the structure of molecules with hydrophobic and polar groups at physiological conditions is of great importance in molecular biology and biotechnology. In particular, amphiphilic molecules that have polar ionizable groups, such as proteins and lipids, can change their structures and functions in response to the pH and the concentration of ions in the solution (3), thereby affecting their physical properties and functions. For example, the structure of lipid membranes affects the structure and activity of membrane-bound proteins (4-6). Furthermore, the intermolecular packing density and structure are known to affect the molecular diffusion rates of water and ions across membranes (7,8). Changing the packing density of molecules within membranes could also be useful for controlling encapsulation and release efficiency of molecules inside a vesicle (9). Additionally the spacing between amphiphilic molecules within a membrane may control the capacity to encapsulate or release...

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“…In Table S1 (in Supplementary Material) are listed the values of the area per lipid (A L ), volume per lipid (V L ), the isothermal area compressibility modulus K A , thickness of the bilayer (D HH ), hydrocarbon thickness (D c ) and Luzzati thicknesses (D B ) for the purpose of literature data that validated molecular simulations of DMPC bilayers Moore et al 2001;Lopez et al 2004;Zubrzycki et al 2000;Gierula et al 1999;Sachs et al 2003;Jämbeck and Lyubartsev 2012). The A L was calculated from the total lateral area of the simulation box divided by the number of lipids in each lipid monolayer.…”

Section: Theoretical Resultsmentioning

confidence: 99%

Experimental and theoretical studies of emodin interacting with a lipid bilayer of DMPC

et al. 2017

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Emodin is one of the most abundant anthraquinone derivatives found in nature. It is the active principle of some traditional herbal medicines with known biological activities. In this work, we combined experimental and theoretical studies to reveal information about location, orientation, interaction and perturbing effects of Emodin on lipid bilayers, where we have taken into account the neutral form of the Emodin (EMH) and its anionic/deprotonated form (EM − ). Using both UV/Visible spectrophotometric techniques and molecular dynamics (MD) simulations, we showed that both EMH and EM − are located in a lipid membrane. Additionally, using MD simulations, we revealed that both forms of Emodin are very close to glycerol groups of the lipid molecules, with the EMH inserted more deeply into the bilayer and more disoriented relative to the normal of the membrane when compared with the EM − , which is more exposed to interfacial water. Analysis of several structural properties of acyl chains of the lipids in a hydrated pure DMPC bilayer and in the presence of Emodin revealed that both EMH and EM − affect the lipid bilayer, resulting in a remarkable disorder of the bilayer in the vicinity of the Emodin. However, the disorder caused by EMH is weaker than that caused by EM − . Our results suggest that these disorders caused by Emodin might lead to distinct effects on lipid bilayers including its disruption which are reported in the literature.

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Hydrogen Bonding Structure and Dynamics of Water at the Dimyristoylphosphatidylcholine Lipid Bilayer Surface from a Molecular Dynamics Simulation

Cited by 161 publications

References 63 publications

Liquid Expanded Monolayers of Lipids As Model Systems to Understand the Anionic Hofmeister Series: 1. A Tale of Models

Liquid Expanded Monolayers of Lipids As Model Systems to Understand the Anionic Hofmeister Series: 1. A Tale of Models

Crystalline polymorphism induced by charge regulation in ionic membranes

Experimental and theoretical studies of emodin interacting with a lipid bilayer of DMPC

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