Tethered or Adsorbed Supported Lipid Bilayers in Nanotubes Characterized by Deuterium Magic Angle Spinning NMR Spectroscopy

Wattraint, Olivier; Warschawski, Dror E.; Sarazin, Catherine

doi:10.1021/la0469147

Cited by 13 publications

(7 citation statements)

References 30 publications

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“…These processes range from passive uptake of small molecules to active processes such as endocytosis and cell signaling. Given the range and importance of lipid membrane chemistry, considerable effort has been made to develop model phospholipid bilayers supported on a range of substrates. − A common approach to forming model membrane systems is the assembly of a phospholipid bilayer on a glass or silica substrate prepared either by fusion of phospholipid vesicles or Langmuir–Blodgett/Langmuir–Schaefer deposition of phospholipids on planar supports. ,− Planar-supported phospholipid bilayers have been employed in a variety of experiments for assessing bilayer structures, , investigating membrane interactions with peptides and proteins, ,− and providing membrane-like supports for ligand binding experiments and biosensing. ,, To increase the surface area for spectroscopic characterization of these structures, supported lipid bilayers have also been deposited by vesicle fusion onto the interior surfaces of porous alumina membranes − and porous silica particles. , …”

Section: Introductionmentioning

confidence: 99%

Confocal Raman Microscopy Investigation of Phospholipid Monolayers Deposited on Nitrile-Modified Surfaces in Porous Silica Particles

et al. 2020

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Phospholipid bilayers deposited on a variety of surfaces provide models for investigation of the lipid membrane structure and supports for biocompatible sensors. Hybrid-supported phospholipid bilayers (HSLBs) are stable membrane models for these investigations, typically prepared by self-assembly of a lipid monolayer over an n-alkane-modified surface. HSLBs have been prepared on nalkyl chain-modified silica and used for lipophilicity-based chromatographic separations. The structure of these hybrid bilayers differs from vesicle membranes where the lipid head group spacing is greater due to interdigitation of the lipid acyl chains with the underlying n-alkyl chains bound to the silica surface. This interdigitated structure exhibits a broader melting transition at a higher temperature due to strong interactions between the lipid acyl chains and the immobile n-alkyl chains bound to silica. In the present work, we seek to reduce the interactions between a lipid monolayer and its supporting substrate by self-assembly of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) on porous silica functionalized with nitrile-terminated surface ligands. The frequency of Raman scattering of the surface −CN stretching mode at the lipid−nitrile interface is consistent with an n-alkane-like environment and insensitive to lipid head group charge, indicating that the lipid acyl chains are in contact with the surface nitrile groups. The head group area of this lipid monolayer was determined from the within-particle phospholipid concentration and silica specific surface area and found to be 54 ± 2 Å 2 , equivalent to the head group area of a DMPC vesicle bilayer. The structure of these nitrile-supported phospholipid monolayers was characterized below and above their melting transition by confocal Raman microscopy and found to be nearly identical to DMPC vesicle bilayers. Their narrow gel-to-fluid-phase melting transition is equivalent to dispersed DMPC vesicles, suggesting that the acyl chain structure on the nitrile support mimics the outer leaflet structure of a vesicle membrane.

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Section: Introductionmentioning

confidence: 99%

Confocal Raman Microscopy Investigation of Phospholipid Monolayers Deposited on Nitrile-Modified Surfaces in Porous Silica Particles

et al. 2020

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“…Recent studies have shown that the new AAO-supported bilayers retain many biophysical properties of unsupported lipid vesicles (19,20), and they are suitable for aligning membrane proteins for high-resolution multidimensional solidstate NMR studies (17). Detailed NMR (17,18,21,22) and DSC (19,20) studies provided further characterization of the biophysical properties of such nanotubular bilayers. Specifically, 31 P NMR studies of POPC (1-palmitoyl-2-oleoyl-snglycero-3 phosphocholine) bilayers absorbed into AAO nanopores indicated that some portions of the bilayer surface were inaccessible to Pr 31 shift reagent when the bilayer was maintained above the main phase transition temperature.…”

Section: Introductionmentioning

confidence: 99%

Flow-Through Lipid Nanotube Arrays for Structure-Function Studies of Membrane Proteins by Solid-State NMR Spectroscopy

Chekmenev

Gor’kov

Cross

et al. 2006

Biophysical Journal

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A novel method for studying membrane proteins in a native lipid bilayer environment by solid-state NMR spectroscopy is described and tested. Anodic aluminum oxide (AAO) substrates with flow-through 175 nm wide and 60-mum-long nanopores were employed to form macroscopically aligned peptide-containing lipid bilayers that are fluid and highly hydrated. We demonstrate that the surfaces of both leaflets of such bilayers are fully accessible to aqueous solutes. Thus, high hydration levels as well as pH and desirable ion and/or drug concentrations could be easily maintained and modified as desired in a series of experiments with the same sample. The method allows for membrane protein NMR experiments in a broad pH range that could be extended to as low as 1 and as high as 12 units for a period of up to a few hours and temperatures as high as 70 degrees C without losing the lipid alignment or bilayers from the nanopores. We demonstrate the utility of this method by a solid-state 19.6 T (17)O NMR study of reversible binding effects of mono- and divalent ions on the chemical shift properties of the Leu(10) carbonyl oxygen of transmembrane pore-forming peptide gramicidin A (gA). We further compare the (17)O shifts induced by binding metal ions to the binding of protons in the pH range from 1 to 12 and find a significant difference. This unexpected result points to a difference in mechanisms for ion and proton conduction by the gA pore. We believe that a large number of solid-state NMR-based studies, including structure-function, drug screening, proton exchange, pH, and other titration experiments, will benefit significantly from the method described here.

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“…Anodic oxidation of aluminum produces γ-alumina with a reproducible pore size in the submicrometer range, high pore density, and a narrow pore size distribution. Several laboratories reported feasibility of depositing phospholipid layers on the cylindrical walls of AAO pores ( − ). The tubular lipid bilayers cover pore walls over their entire length.…”

mentioning

confidence: 99%

Functional Reconstitution of Rhodopsin into Tubular Lipid Bilayers Supported by Nanoporous Media

et al. 2006

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We report on a novel reconstitution method for G-protein-coupled receptors (GPCRs) that yields detergent-free, single, tubular membranes in porous anodic aluminum oxide (AAO) filters at concentrations sufficient for structural studies by solid-state NMR. The tubular membranes line the inner surface of pores that traverse the filters, permitting easy removal of detergents during sample preparation as well as delivery of ligands for functional studies. Reconstitution of bovine rhodopsin into AAO filters did not interfere with rhodopsin function. Photoactivation of rhodopsin in AAO pores, monitored by UV-vis spectrophotometry, was indistinguishable from rhodopsin in unsupported unilamellar liposomes. The rhodopsin in AAO pores is G-protein binding competent as shown by a [35S]GTPgammaS binding assay. The lipid-rhodopsin interaction was investigated by 2H NMR on sn-1- or sn-2-chain perdeuterated 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phospholine as a matrix lipid. Rhodopsin incorporation increased mosaic spread of bilayer orientations and contributed to spectral density of motions with correlation times in the range of nano- to microseconds, detected as a significant reduction in spin-spin relaxation times. The change in lipid chain order parameters due to interaction with rhodopsin was insignificant.

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Tethered or Adsorbed Supported Lipid Bilayers in Nanotubes Characterized by Deuterium Magic Angle Spinning NMR Spectroscopy

Cited by 13 publications

References 30 publications

Confocal Raman Microscopy Investigation of Phospholipid Monolayers Deposited on Nitrile-Modified Surfaces in Porous Silica Particles

Confocal Raman Microscopy Investigation of Phospholipid Monolayers Deposited on Nitrile-Modified Surfaces in Porous Silica Particles

Flow-Through Lipid Nanotube Arrays for Structure-Function Studies of Membrane Proteins by Solid-State NMR Spectroscopy

Functional Reconstitution of Rhodopsin into Tubular Lipid Bilayers Supported by Nanoporous Media

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