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Start Over Descriptor "Bilayers" Journal biophysical chemistry
5 results on '"Bilayers"'

1. How to best estimate the viscosity of lipid bilayers

Author

Gamal Rayan, Martin Picard, Wladimir Urbach, Vladimir Adrien, Isabelle Broutin, Ksenia Astafyeva, Nicolas Taulier, Patrick F.J. Fuchs, Laboratoire de physique de l'ENS - ENS Paris (LPENS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Cibles Thérapeutiques et conception de médicaments (CiTCoM - UMR 8038), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de biologie physico-chimique des protéines membranaires (LBPC-PM (UMR_7099)), Institut de biologie physico-chimique (IBPC (FR_550)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire des biomolécules (LBM UMR 7203), Chimie Moléculaire de Paris Centre (FR 2769), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département de Chimie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Mécanismes Moléculaires Membranaires, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Laboratoire d'Imagerie Biomédicale (LIB), Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Taulier, Nicolas, Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-École normale supérieure - Paris (ENS Paris), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Département de Chimie - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Chimie Moléculaire de Paris Centre (FR 2769), Institut de Chimie du CNRS (INC)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)

Subjects
Fluorescence-lifetime imaging microscopy, FLIM, Diffusion, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Lipid Bilayers, Biophysics, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Biochemistry, lipids, Viscosity, Lipid bilayer, Molecular diffusion, [PHYS.PHYS.PHYS-BIO-PH] Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Chemistry, Bilayer, Organic Chemistry, Fluorescence recovery after photobleaching, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Membrane, Microscopy, Fluorescence, Chemical physics, FRAP, Hydrodynamics, fluorescence, 0210 nano-technology, bilayers
Abstract

The viscosity of lipid bilayers is a property relevant to biological function, as it affects the diffusion of membrane macromolecules. To determine its value, and hence portray the membrane, various literature-reported techniques lead to significantly different results. Herein we compare the results issuing from two widely used techniques to determine the viscosity of membranes: the Fluorescence Lifetime Imaging Microscopy (FLIM), and Fluorescence Recovery After Photobleaching (FRAP). FLIM relates the time of rotation of a molecular rotor inserted into the membrane to the macroscopic viscosity of a fluid. Whereas FRAP measures molecular diffusion coefficients. This approach is based on a hydrodynamic model connecting the mobility of a membrane inclusion to the viscosity of the membrane. We show that: - The first method is very sensitive to local changes in viscosity; however, most often it would only provide the viscosity of the hydrophobic part of the membrane. - The membrane viscosity is adequately estimated when the hydrodynamic model approach is applied to the mobility of micrometric size membrane inclusion but not for nanometric size inclusions such as lipids or proteins. In this case, the calculated value extracted from the same hydrodynamic model characterizes the interaction of the given nano-inclusion with the bilayer instead of the bilayer viscosity. This article emphasizes the pitfalls to be avoided and the rules to be observed in order to obtain a value of the bilayer viscosity that characterizes the bilayer instead of interactions between the bilayer and the embedded probe.

Published
2021
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2. Effect of the interfacial tension and ionic strength on the thermodynamic barrier associated to the benzocaine insertion into a cell membrane

Author

López Cascales, J.J. and Oliveira Costa, S.D.

Subjects
*SURFACE tension, *IONIZATION (Atomic physics), *BENZOCAINE, *CELL membranes, *ANESTHETICS, *SODIUM bicarbonate, *PHOSPHOLIPIDS, *THERMODYNAMICS
Abstract

Abstract: The insertion of local anaesthetics into a cell membrane is a key aspect for explaining their activity at a molecular level. It has been described how the potency and response time of local anaesthetics is improved (for clinical applications) when they are dissolved in a solution of sodium bicarbonate. With the aim of gaining insight into the physico-chemical principles that govern the action mechanism of these drugs at a molecular level, simulations of benzocaine in binary lipid bilayers formed by DPPC/DPPS were carried out for different ionic strengths of the aqueous solution. From these molecular dynamic simulations, we observed how the thermodynamic barrier associated with benzocaine insertion into the lipid bilayers diminished exponentially as the fraction of DPPS in the bilayer increased, especially when the ionic strength of the aqueous solution increased. In line with these results, we also observed how this thermodynamic barrier diminished exponentially with the phospholipid/water interfacial tension. [Copyright &y& Elsevier]

Published
2013
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3. How to best estimate the viscosity of lipid bilayers.

Author

Adrien, Vladimir, Rayan, Gamal, Astafyeva, Ksenia, Broutin, Isabelle, Picard, Martin, Fuchs, Patrick, Urbach, Wladimir, and Taulier, Nicolas

Subjects
*VISCOSITY, *BILAYER lipid membranes, *MOLECULAR rotation, *MOLECULAR probes, *DIFFUSION coefficients
Abstract

The viscosity of lipid bilayers is a property relevant to biological function, as it affects the diffusion of membrane macromolecules. To determine its value, and hence portray the membrane, various literature-reported techniques lead to significantly different results. Herein we compare the results issuing from two widely used techniques to determine the viscosity of membranes: the Fluorescence Lifetime Imaging Microscopy (FLIM), and Fluorescence Recovery After Photobleaching (FRAP). FLIM relates the time of rotation of a molecular rotor inserted into the membrane to the macroscopic viscosity of a fluid. Whereas FRAP measures molecular diffusion coefficients. This approach is based on a hydrodynamic model connecting the mobility of a membrane inclusion to the viscosity of the membrane. We show that: - The first method is very sensitive to local changes in viscosity; however, most often it would only provide the viscosity of the hydrophobic part of the membrane. - The membrane viscosity is adequately estimated when the hydrodynamic model approach is applied to the mobility of micrometric size membrane inclusion but not for nanometric size inclusions such as lipids or proteins. In this case, the calculated value extracted from the same hydrodynamic model characterizes the interaction of the given nano-inclusion with the bilayer instead of the bilayer viscosity. This article emphasizes the pitfalls to be avoided and the rules to be observed in order to obtain a value of the bilayer viscosity that characterizes the bilayer instead of interactions between the bilayer and the embedded probe. [Display omitted] • FLIM measurements most likely do not report the exact bilayer viscosity. • Molecular probes in FRAP lead to erroneous viscosity values. • Micrometric-sized probes in FRAP lead to correct viscosity values. [ABSTRACT FROM AUTHOR]

Published
2022
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4. Existence of lipid microdomains in bilayer of dipalmitoyl phosphatidylcholine (DPPC) and 1-stearoyl-2-docosahexenoyl phosphatidylserine (SDPS) and their perturbation by chlorpromazine : A 13C and 31P solid-state NMR study

Author

Song, Chen, Holmsen, Holm, and Nerdal, Willy

Subjects
*LIPIDS, *DOCOSAHEXAENOIC acid, *FATTY acids, *CARBOXYLIC acids
Abstract

Abstract: The polyunsaturated fatty acid docosahexaenoic acid (DHA, 22:6, n-3) is found at a level of about 50% in the phospholipids of neuronal tissue membranes and appears to be crucial to human health. Dipalmitoyl phosphatidylcholine (DPPC, 16:0/16:0 PC) and the DHA containing 1-stearoyl-2-docosahexenoyl phosphatidylserine (SDPS) were used to make DPPC (60%)/SDPS (40%) bilayers with and without 10 mol% chlorpromazine (CPZ), a cationic, amphiphilic phenothiazine. Resonances that are present in 13C NMR spectrum of the DPPC (60%)/SDPS (40%) sample and that disappear in presence of 10% CPZ most probably are due to the special interface environment, e.g. the hydrophobic mismatch, at the interface of DPPC and SDPS microdomains in the DPPC/SDPS bilayer. In itself the appearance of resonances at novel chemical shift values is a clear demonstration of a unique chemical environment in the DPPC (60%)/SDPS (40%) bilayer. The findings of the study presented here suggest CPZ bound to the phosphate of SDPS will slow down and partially inhibit such a DHA acyl chain movement in the DPPC/SDPS bilayer. This would affect the area occupied by a SDPS molecule (in the bilayer) and probably the thickness of the bilayer where SDPS molecules reside as well. It is quite likely that such CPZ caused changes can affect the function of proteins embedded in the bilayer. [Copyright &y& Elsevier]

Published
2006
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5. Depth-dependent analysis of membranes using benzophenone-based phospholipids

Author

Anil K. Lala, E. Ravi Kumar, and Bino John

Subjects
Light, Nitrene, Lipid Bilayers, Reactive intermediate, Normal Distribution, Biophysics, Inter-Molecular Crosslinking, Photoaffinity Labels, Hydrophobic Core, Photochemistry, Biochemistry, Fluorescence, Mass Spectrometry, Depth-Dependent Analysis, Benzophenones, chemistry.chemical_compound, Acid, Cross-Linking, Benzophenone, Reagent, Organic chemistry, Reactivity (chemistry), Fatty Acyl Chains, Benzophenone-Based Phospholipids, Phospholipids, Molecular Structure, Chemistry, Vesicle, Bilayer, Organic Chemistry, Phosphatidylcholine, Cross-Linking Reagents, Membrane, Bilayers, Gaussian, Dimyristoylphosphatidylcholine, Dimerization
Abstract

Any attempt to probe the membrane hydrophobic core with chemical reagents necessitates the use of reactive intermediates like carbenes and nitrenes, which can insert into C-H bonds. Several photoactivable reagents based on carbenes and nitrenes have been reported. However, the high reactivity of these reagents, often leads to very low insertion yields. We report here a high degree of cross-linking (35-40%) achieved with three benzophenone-based phospholipids and analyze the carbon functionalization data using a multiple Gaussian function. These phospholipids are so designed so as to permit depth-dependent labeling in membranes. Single bilayer vesicles were prepared from these phospholipids and dimyristoylphosphatidylcholine. The cross-linked product was isolated and characterized by mass spectroscopy. The results obtained indicated that the cross-linked product was dominated by dimeric product formed by intermolecular cross-linking. The Gaussian analysis used here provides insight into the relative depths of the probes inside the membrane. (C) 2000 .

Published
2000
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