scholarly journals Interaction of the Macrolide Antibiotic Azithromycin with Lipid Bilayers: Effect on Membrane Organization, Fluidity, and Permeability

2005 ◽  
Vol 22 (3) ◽  
pp. 465-475 ◽  
Author(s):  
A. Berquand ◽  
N. Fa ◽  
Y. F. Dufr�ne ◽  
M.-P. Mingeot-Leclercq
Keyword(s):  
Lipid Bilayers ◽  
Macrolide Antibiotic ◽  
Membrane Organization

scholarly journals The Bacteriostatic Activity of 2-Phenylethanol Derivatives Correlates with Membrane Binding Affinity

Membranes ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 254
Author(s):  
Isabel S. Kleinwächter ◽  
Stefanie Pannwitt ◽  
Alessia Centi ◽  
Nadja Hellmann ◽  
Eckhard Thines ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Hydrophobic Interactions ◽  
Bacteriostatic Activity ◽  
Hydrophobic Core ◽  
Membrane Organization ◽  
Primary Alcohols ◽  
Phenyllactic Acid ◽  
Aromatic Alcohols ◽  
The Impact ◽  
Methyl Phenylacetate

The hydrophobic tails of aliphatic primary alcohols do insert into the hydrophobic core of a lipid bilayer. Thereby, they disrupt hydrophobic interactions between the lipid molecules, resulting in a decreased lipid order, i.e., an increased membrane fluidity. While aromatic alcohols, such as 2-phenylethanol, also insert into lipid bilayers and disturb the membrane organization, the impact of aromatic alcohols on the structure of biological membranes, as well as the potential physiological implication of membrane incorporation has only been studied to a limited extent. Although diverse targets are discussed to be causing the bacteriostatic and bactericidal activity of 2-phenylethanol, it is clear that 2-phenylethanol severely affects the structure of biomembranes, which has been linked to its bacteriostatic activity. Yet, in fungi some 2-phenylethanol derivatives are also produced, some of which appear to also have bacteriostatic activities. We showed that the 2-phenylethanol derivatives phenylacetic acid, phenyllactic acid, and methyl phenylacetate, but not Tyrosol, were fully incorporated into model membranes and affected the membrane organization. Furthermore, we observed that the propensity of the herein-analyzed molecules to partition into biomembranes positively correlated with their respective bacteriostatic activity, which clearly linked the bacteriotoxic activity of the substances to biomembranes.

scholarly journals Effect of Line Tension on the Lateral Organization of Lipid Membranes

2007 ◽  
Vol 282 (46) ◽  
pp. 33537-33544 ◽  
Author(s):  
Ana J. García-Sáez ◽  
Salvatore Chiantia ◽  
Petra Schwille
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Acyl Chain ◽  
Line Tension ◽  
Theoretical Work ◽  
Time Lapse ◽  
Domain Growth ◽  
Domain Formation ◽  
Membrane Organization ◽  
Cellular Membranes

The principles of organization and functioning of cellular membranes are currently not well understood. The raft hypothesis suggests the existence of domains or rafts in cell membranes, which behave as protein and lipid platforms. They have a functional role in important cellular processes, like protein sorting or cell signaling, among others. Theoretical work suggests that the interfacial energy at the domain edge, also known as line tension, is a key parameter determining the distribution of domain sizes, but there is little evidence of how line tension affects membrane organization. We have investigated the effects of the line tension on the formation and stability of liquid ordered domains in model lipid bilayers with raft-like composition by means of time-lapse confocal microscopy coupled to atomic force microscopy. We varied the hydrophobic mismatch between the two phases, and consequently the line tension, by modifying the thickness of the disordered phase with phosphatidylcholines of different acyl chain length. The temperature of domain formation, the dynamics of domain growth, and the distribution of domain sizes depend strongly on the thickness difference between the domains and the surrounding membrane, which is related to line tension. When considering line tension calculated from a theoretical model, our results revealed a linear increase of the temperature of domain formation and domain growth rate with line tension. Domain budding was also shown to depend on height mismatch. Our experiments contribute significantly to our knowledge of the physical-chemical parameters that control membrane organization. Importantly, the general trends observed can be extended to cellular membranes.

Observation of Concanavalin-A receptors on hydrated planar erythrocyte membrane film by in situ electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 608-609
Author(s):  
Neng-Bo He ◽  
S.W. Hui
Keyword(s):  
Lipid Bilayers ◽  
Erythrocyte Membrane ◽  
Lipid Membranes ◽  
Surface Film ◽  
Biological Membranes ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Black Lipid Membranes ◽  
Fine Mesh ◽  
Planar Films

Monolayers and planar "black" lipid membranes have been widely used as models for studying the structure and properties of biological membranes. Because of the lack of a suitable method to prepare these membranes for electron microscopic observation, their ultrastructure is so far not well understood. A method of forming molecular bilayers over the holes of fine mesh grids was developed by Hui et al. to study hydrated and unsupported lipid bilayers by electron diffraction, and to image phase separated domains by diffraction contrast. We now adapted the method of Pattus et al. of spreading biological membranes vesicles on the air-water interfaces to reconstitute biological membranes into unsupported planar films for electron microscopic study. hemoglobin-free human erythrocyte membrane stroma was prepared by hemolysis. The membranes were spreaded at 20°C on balanced salt solution in a Langmuir trough until a surface pressure of 20 dyne/cm was reached. The surface film was repeatedly washed by passing to adjacent troughs over shallow partitions (fig. 1).

Ultrastructural autoradiography of L6 skeletal-muscle cells exposed to a tritiated macrolide antibiotic (LY237216) in vitro

1992 ◽  
Vol 50 (1) ◽  
pp. 612-613
Author(s):  
S.L. White ◽  
C.B. Jensen ◽  
D.D. Giera ◽  
D.A. Laska ◽  
M.N. Novilla ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Quantitative Analysis ◽  
Macrolide Antibiotic ◽  
Circle Method ◽  
Apical Surface ◽  
Polycarbonate Membrane ◽  
L6 Cells ◽  
Low Viscosity ◽  
Erythromycin A

In vitro exposure to LY237216 (9-Deoxo-11-deoxy-9,11-{imino[2-(2-methoxyethoxy)ethylidene]-oxy}-(9S)-erythromycin), a macrolide antibiotic, was found to induce cytoplasmic vacuolation in L6 skeletal muscle myoblast cultures (White, S.L., unpubl). The present study was done to determine, by autoradiographic quantitative analysis, the subcellular distribution of 3H-LY237216 in L6 cells.L6 cells (ATCC, CRL 1458) were cultured to confluency on polycarbonate membrane filters (Millipore Corp., Bedford, MA) in M-199 medium (GIBCO® Labs) with 10% fetal bovine serum. The cells were exposed from the apical surface for 1-hour to unlabelled-compound (0 μCi/ml) or 50 (μCi/ml of 3H-LY237216 at a compound concentration of 0.25 mg/ml. Following a rapid rinse in compound-free growth medium, the cells were slam-frozen against a liquid nitrogen cooled, polished copper block in a CF-100 cryofixation unit (LifeCell Corp., The Woodlands, TX). Specimens were dried in the MDD-C Molecular Distillation Drier (LifeCell Corp.), vapor osmicated and embedded in Spurrs low viscosity resin. Ultrathin sections collected on formvar coated stainless steel grids were counter-stained, then individually mounted on corks. A monolayer of Ilford L4 nuclear emulsion (Polysciences, Inc., Warrington, PA) was placed on the sections, utilizing a modified “loop method”. The emulsions were exposed for 7-weeks in a light-tight box at 4°C. Autoradiographs were developed in Microdol-X developer and examined on a Philips EM410LS transmission electron microscope. Quantitative analysis of compound localization employed the point and circle approach of Williams; incorporating the probability circle method of Salpeter and McHenry.

Effect of Integral Proteins on Frozen Membrane Fracture

1980 ◽  
Vol 38 ◽  
pp. 756-759 ◽  
Author(s):  
S. Kirchanski ◽  
D. Branton
Keyword(s):  
Lipid Bilayers ◽  
Freeze Fracture ◽  
Covalent Bond ◽  
Erythrocyte Membranes ◽  
Glycophorin A ◽  
Experimental Protocol ◽  
Transmembrane Glycoprotein ◽  
Bond Breakage ◽  
Human Erythrocyte Membranes ◽  
Integral Proteins

We have investigated the effect of integral membrane proteins upon the fracturing of frozen lipid bilayers. This investigation has been part of an effort to develop freeze fracture labeling techniques and to assess the possible breakage of covalent protein bonds during the freeze fracture process. We have developed an experimental protocol utilizing lectin affinity columns which should detect small amounts of covalent bond breakage during the fracture of liposomes containing purified (1) glycophorin (a transmembrane glycoprotein of human erythrocyte membranes). To fracture liposomes in bulk, frozen liposomes are ground repeatedly under liquid nitrogen. Failure to detect any significant covalent bond breakage (contrary to (2)) led us to question the effectiveness of our grinding procedure in fracturing and splitting lipid bilayers.

Late Stages of the “Pearling" Instability in Lipid Bilayers

1997 ◽  
Vol 7 (9) ◽  
pp. 1185-1204 ◽  
Author(s):  
J. L. Coveas ◽  
S. T. Milner ◽  
W. B. Russel
Keyword(s):  
Lipid Bilayers ◽  
Late Stages

Improved micro-impedance spectroscopy to determine cell barrier properties

2020 ◽  
Vol 4 (3) ◽  
pp. 150-155 ◽  
Author(s):  
Md. Mehadi Hasan Sohag ◽  
Olivier Nicoud ◽  
Racha Amine ◽  
Abir Khalil-Mgharbel ◽  
Jean-Pierre Alcaraz ◽  
...  
Keyword(s):  
Impedance Spectroscopy ◽  
Epithelial Cells ◽  
Lipid Bilayers ◽  
Cultured Cells ◽  
Cell Model ◽  
Measurement Techniques ◽  
Cell Monolayer ◽  
Microfluidic Channel ◽  
Small Surface ◽  
Resistance Pathway

AbstractThe goal of this study was to determine whether the Tethapod system, which was designed to determine the impedance properties of lipid bilayers, could be used for cell culture in order to utilise micro-impedance spectroscopy to examine further biological applications. To that purpose we have used normal epithelial cells from kidney (RPTEC) and a kidney cancer cell model (786-O). We demonstrate that the Tethapod system is compatible with the culture of 10,000 cells seeded to grow on a small area gold measurement electrode for several days without affecting the cell viability. Furthermore, the range of frequencies for EIS measurements were tuned to examine easily the characteristics of the cell monolayer. We demonstrate significant differences in the paracellular resistance pathway between normal and cancer kidney epithelial cells. Thus, we conclude that this device has advantages for the study of cultured cells that include (i) the configuration of measurement and reference electrodes across a microfluidic channel, and (ii) the small surface area of 6 parallel measurement electrodes (2.1 mm2) integrated in a microfluidic system. These characteristics might improve micro-impedance spectroscopy measurement techniques to provide a simple tool for further studies in the field of the patho-physiology of biological barriers.

Direct Measurement of Charge Reversal on Lipid Bilayers using Heterodyne-Detected Second Harmonic Generation Spectroscopy

2019 ◽  
Author(s):  
HanByul Chang ◽  
Paul Ohno ◽  
Yangdongling Liu ◽  
Franz Geiger
Keyword(s):  
Lipid Bilayers ◽  
Surface Potential ◽  
Second Harmonic ◽  
Fluid Phase ◽  
Cationic Polyelectrolyte ◽  
Charge Reversal ◽  
Buried Interfaces ◽  
Phase Transition Temperatures ◽  
Complementary Techniques ◽  
Order Susceptibility

We report the detection of charge reversal induced by the adsorption of a cationic polyelectrolyte, poly(allylamine) hydrochloride (PAH), to buried supported lipid bilayers (SLBs), used as idealized model biological membranes. We observe changes in the surface potential in isolation from other contributors to the total SHG response by extracting the phase-shifted potential-dependent third-order susceptibility from the overall SHG signal. We demonstrate the utility of this technique in detecting both the sign of the surface potential and the point of charge reversal at buried interfaces without any prior information or complementary techniques<i>.</i>Furthermore, isolation of the second-order susceptibility contribution from the overall SHG response allows us to directly monitor changes in the Stern Layer. Finally, we characterize the Stern and Diffuse Layers over single-component SLBs formed from three different zwitterionic lipids of different gel-to-fluid phase transition temperatures (T<sub>m</sub>s). We determine whether the surface potential changes with the physical phase state (gel, transitioning, or fluid) of the SLB and incorporate 20 percent of negatively charged lipids to the zwitterionic SLB to investigate how the surface potential changes with surface charge.

Influence of Brain Gangliosides on the Formation and Properties of Supported Lipid Bilayers for Binding Kinetics Studies

2018 ◽  
Author(s):  
Luke Jordan ◽  
Nathan Wittenberg
Keyword(s):  
Lipid Bilayers ◽  
Binding Kinetics ◽  
Supported Lipid Bilayers ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Supported Lipid Bilayer ◽  
Head Groups ◽  
Lipid Diffusion ◽  
Kinetics Of ◽  
Brain Gangliosides

This is a comprehensive study of the effects of the four major brain gangliosides (GM1, GD1b, GD1a, and GT1b) on the adsorption and rupture of phospholipid vesicles on SiO2 surfaces for the formation of supported lipid bilayer (SLB) membranes. Using quartz crystal microbalance with dissipation monitoring (QCM-D) we show that gangliosides GD1a and GT1b significantly slow the SLB formation process, whereas GM1 and GD1b have smaller effects. This is likely due to the net ganglioside charge as well as the positions of acidic sugar groups on ganglioside glycan head groups. Data is included that shows calcium can accelerate the formation of ganglioside-rich SLBs. Using fluorescence recovery after photobleaching (FRAP) we also show that the presence of gangliosides significantly reduces lipid diffusion coefficients in SLBs in a concentration-dependent manner. Finally, using QCM-D and GD1a-rich SLB membranes we measure the binding kinetics of an anti-GD1a antibody that has similarities to a monoclonal antibody that is a hallmark of a variant of Guillain-Barre syndrome.

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