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Model Membrane Systems (model + membrane_system)
Selected AbstractsCombined AFM and Two-Focus SFCS Study of Raft-Exhibiting Model Membranes,CHEMPHYSCHEM, Issue 11 2006Salvatore Chiantia Abstract Dioleoylphosphatidylcholine/sphingomyelin/cholesterol (DOPC/SM/cholesterol) model membranes exhibit liquid,liquid phase separation and therefore provide a physical model for the putative liquid-ordered domains present in cells. Here we present a combination of atomic force microscopy (AFM) imaging, force measurements, confocal fluorescence imaging and two-focus scanning fluorescence correlation spectroscopy (two-focus SFCS) to obtain structural and dynamical information about this model membrane system. Partition coefficients and diffusion coefficients in the different phases were measured with two-focus SFCS for numerous fluorescent lipid analogues and proteins, while being directly related to the lateral organization of the membrane and its mechanical properties probed by AFM. Moreover we show how the combination of these different approaches is effective in reducing artifacts resulting from the use of a single technique. [source] Solid-state NMR Structure DeterminationIUBMB LIFE, Issue 9 2003Alison Drechsler Abstract Biological applications of solid-state NMR (SS-NMR) have been predominantly in the area of model membrane systems. Increasingly the focus has been membrane peptides and proteins. SS-NMR is able to provide information about how the peptides or proteins interact with the lipids or other peptides/proteins in the membrane, their effect on the membrane and the location of the peptides or proteins relative to the membrane surface. Recent developments in biological SS-NMR have been made possible by improvements in labelling and NMR techniques. This review discusses aligned systems and magic angle spinning techniques, bilayers and bicelles, and measurement of chemical shift anisotropy and dipolar coupling. A number of specific experiments such as cross polarization, rotational resonance, REDOR, PISEMA, MAOSS and multidimensional experiments are described. In addition to 2H, 13C and 15N, recent solid-sate 1H, 19F and 17O NMR work is discussed. Several examples of the use of SS-NMR to determine the structure of membrane peptides and proteins are given. IUBMB Life, 55: 515-523, 2003 [source] Synthesis of 15N-, 13C-, and 2H-labeled methanandamide analogsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 2 2003Fen-Mei Yao Abstract Four isotopically labeled, metabolically stable analogs of arachidony-lethanolamide (anandamide), an endogenous cannabinoid ligand, were synthesized via a five-step reaction sequence starting from arachidonic acid. These stable methanandamide derivatives will serve as probes for studying the conformational properties of anandamide in model membrane systems using solid-state NMR spectroscopy. The synthetic methods described can be applied to the preparations of other anandamide analogs with isotopic labeling in different positions of the molecule, which could be utilized in biochemical and pharmacological experiments. Copyright © 2002 John Wiley & Sons, Ltd. [source] Advances in membrane receptor screening and analysisJOURNAL OF MOLECULAR RECOGNITION, Issue 4 2004Matthew A. Cooper Abstract During the last decade there has been significant progress in the development of analytical techniques for the screening of ligand binding to membranes and membrane receptors. This review focuses on developments using label-free assays that facilitate ligand,membrane,receptor screening without the need for chemical-, biological- or radiological-labelled reagents. These assays include acoustic, optical surface plasmon resonance biosensing, sedimentation (analytical ultracentrifugation), chromatographic assays, isothermal titration calorimetry and differential scanning calorimetry. The merits and applications of cell-based screening systems and of different model membrane systems, including planar supported lipid layers, bead-supported membranes and lipid micro-arrays, are discussed. Recent advances involving more established techniques including intrinsic fluorescence, FRET spectroscopy, scintillation proximity assays and automated patch clamping are presented along with applications to peripheral membrane proteins, ion channels and G protein-coupled receptors. Novel high-throughput assays for determination of drug- and protein-partitioning in membranes are also highlighted. To aid the experimenter, a brief synopsis of the techniques commonly employed to purify and reconstitute membranes and membrane receptors is included. Copyright © 2004 John Wiley & Sons, Ltd [source] Probing Biomembrane Dynamics by Dual-Wavelength Reflection Interference Contrast MicroscopyCHEMPHYSCHEM, Issue 16 2009Cornelia Monzel Abstract We present an improved analysis of reflection interference contrast microscopy (RICM) images, recorded to investigate model membrane systems that mimic cell adhesion. The model systems were giant unilamellar vesicles (GUV) adhering via specific ligand,receptor interactions to supported lipid bilayers (SLB) or to patterns of receptors. Conventional RICM and dual-wavelength RICM (DW,RICM) were applied to measure absolute optical distances between the biomembranes and planar substrates. We developed algorithms for a straightforward implementation of an automated, time-resolved reconstruction of the membrane conformations from RICM/DW,RICM images, taking into account all the interfaces in the system and blurring of the data due to camera noise. Finally, we demonstrate the validity and usefulness of this new approach by analyzing the topography and fluctuations of a bound membrane in the steady state and its dynamic adaptation to osmotic pressure changes. These measurements clearly show that macroscopic membrane flow through tightly adhered area is possible in our system. [source] | ||||||||||