Dielectric studies on water in solutions of purified lecithin vesicles

Kaatze, U.; Dittrich, A.; Göpel, K.-D.; Pottel, R.

doi:10.1016/0009-3084(84)90052-5

Cited by 25 publications

(9 citation statements)

References 17 publications

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“…BIOPHYSICAL JOURNAL VOLUME 50 1986 dielectric constant measured by Kaatze et al (ee, = 10.7; see reference 6), but is very far from the values measured at low frequencies (6,7). This fact clearly indicates that a disordered crystalline-like picture of the polar head groups region is not the correct one.…”

Section: Dielectric Constant Of the Interface Regionmentioning

confidence: 75%

“…We obtain e(z) = C0 exph(zo + r cos 0) = E(zo) exp h r cos 0. Combining the previous equations with 4c = -'12S, one obtains the following expression for the potential outside the cavity containing the studied molecule +n = E E C'fn (r) eh/2'c P' (cos 0) elm, (6) (i= z z Bnm r"Pm (cos 0)e"'0.…”

Section: -E 47rmentioning

confidence: 99%

“…On the other hand, a recent series of papers devoted to the study of the dielectric relaxation properties of phospholipid vescicles, clearly shows much larger values of the dielectric constant arising from the rotation of the polar head groups in a plane parallel to the membrane surface Dr. Raudino's present address is Department of Chemistry, University of Catania, V. A. Doria 8, 95125, Catania, Italy. (6,7). This last model seems to agree very well with the one used to rationalize nuclear magnetic resonance (NMR) data of the choline group (8).…”

Section: Introductionmentioning

confidence: 99%

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Dielectric properties of the polar head group region of zwitterionic lipid bilayers

Raudino¹,

Mauzerall²

1986

Biophysical Journal

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A theoretical model describing the dielectric properties of the lipid membrane-water interface region was developed. The rotating polar head groups (e.g. phosphatidylcholine) were simulated as a collection of interacting dipoles imbedded in a nonhomogeneous dielectric. The interactions between the nearest neighborhood were explicitly taken into account, while the other interactions were evaluated by means of the continuum theories. The values of the dielectric constant, its anisotropy and the spontaneous polarization of the interface were evaluated. As an application, we calculated the energy of interaction between an ion and the membrane polar head group region. The results indicate a small spontaneous polarization of the interface (1-1.7 Debyes per lipid molecule) due to the tilting angle of the choline residue with respect to the membrane surface. This dipolar field partially compensates that of opposite orientation originating from the ester group region, giving calculated overall dipolar potentials in better agreement with the experimental data. Our model suggests also a very strong dielectric anisotropy of the interface region, the component of the dielectric constant perpendicular to the membrane plane being much smaller than the parallel component.

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Section: Dielectric Constant Of the Interface Regionmentioning

confidence: 75%

Section: -E 47rmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dielectric properties of the polar head group region of zwitterionic lipid bilayers

Raudino¹,

Mauzerall²

1986

Biophysical Journal

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“…In order to make the simulation similar to the conditions in which the ESR experiments were carried out, the following parameters were used: T ¼ 295 K -corresponding to the temperature of lecithin in the ESR experiment, 2a ¼ 0.50 nm -approximate dimensions of polar heads of phospholipids (Kubica, 2001;Möhwald, 1990;Stigter et al, 1992), " r ¼ 10approximate value of the dielectric constant for the area of phospholipid head-groups (Kaatze et al, 1984;Nimtz et al, 1985).…”

Section: Computer Simulationsmentioning

confidence: 99%

Two-step impact of Amphotericin B (AmB) on lipid membranes: ESR experiment and computer simulations

Man

Olchawa

2013

Journal of Liposome Research

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In this study, the electron spin resonance (ESR) method was used to examine the effect of Amphotericin B (AmB) molecules on the fluidity of model membranes made of dipalmitoylphosphatidylcholine (DPPC). The changes occurring under increased AmB concentrations in the spectroscopic parameters of spin probes placed in liposomes were determined. Three probes were used, penetrating the membrane at different depths which allowed the changes in its fluidity to be found in the transverse section. A computer model of the surface layer of membrane, with AmB admixture, was developed and subjected to computer simulation. The effect of changing concentration of the admixture on the binding energy in the system of dipoles representing the surface of the membrane was examined. The ESR studies showed that the process of accumulation of AmB molecules in the membrane has two stages, marked by local maxima in the ESR spectra. The first appears for concentrations of ca. 0.25-0.5% and the second appears for ca. 2.5-3% AmB of its molar ratio to DPPC. The computer simulations permitted reconstructing the two-stage mechanism of interaction between the molecules and the membrane. They demonstrated that, at low concentrations, the AmB molecules position themselves flat on the membrane surface. After the threshold concentration is exceeded, they re-orientate to a vertical position. This process leads to the perforation of the membrane.

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“…8 Studies of phosphatidylcholine ͑PC͒ bilayers at low and full hydration suggest that translational motion of water near the membrane surface is restricted. 14,15 The self-diffusion coefficient of water in the first hydration layer has been reported to be as much as five times smaller than in bulk. 16 The presence of an interface also induces other changes: density of water in the interfacial region is increased 17,18 and the freezing point of the interbilayer water is depressed [19][20][21][22] The network of hydrogen bonds in the interfacial region is perturbed, the probability of water molecules hydrogen bonding with neighboring molecules is increased, but due to a decrease in the number of neighbors, the total number of hydrogen bonds actually decreases 23 In the interfacial region, water is also hydrogen bonded with lipid headgroups; the lifetime of such bonding is five to eight times longer than that of water-water hydrogen bonds.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of water at membrane surfaces: Effect of headgroup structure

Murzyn

Zhao²,

Karttunen

et al. 2006

Biointerphases

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Róg, T. (2006). Dynamics of water at membrane surfaces : effect of headgroup structure. Biointerphases, 1(3), 98-105. DOI: 10.1116/1.2354573 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Atomistic molecular dynamics simulations of fully hydrated 1-palmitoyl-2-oleoylphosphatidylcholine ͑POPC͒, 1-palmitoyl-2-oleoyl-phosphatidylethanolamine ͑POPE͒, and 1-palmitoyl-2-oleoyl-phosphatidylglycerol ͑POPG͒ bilayers in the liquid-crystalline state were carried out to investigate the effect of different lipid headgroups on the dynamics of water at the bilayer surface in short 80 ps time scales. Results obtained in these studies show that the hydrogen bonding amine group of POPE and the glycerol group of POPG slow water motion more than the equivalent choline group of POPC. Therefore, it is surprising that the effect of a POPC bilayer surface on water dynamics is similar to that of POPE and POPG bilayers. That result is due to a much higher number of water molecules interacting with the choline group of POPC than hydrogen-bonded molecules interacting with amine or glycerol groups of POPE and POPG.

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Dielectric studies on water in solutions of purified lecithin vesicles

Cited by 25 publications

References 17 publications

Dielectric properties of the polar head group region of zwitterionic lipid bilayers

Dielectric properties of the polar head group region of zwitterionic lipid bilayers

Two-step impact of Amphotericin B (AmB) on lipid membranes: ESR experiment and computer simulations

Dynamics of water at membrane surfaces: Effect of headgroup structure

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