Homogeneous arrays of hexagonally packed nanopores of 50-90 nm in diameter formed in alumina ceramics provide a versatile substrate for macroscopic alignment of lipid bilayer membranes.  In such hybrid nanotubular structures individual lipids lay perpendicular to the pore direction within 1-2 degree of mosaic spread while phase properties of lipid bilayers remain essentially unaffected.  The lipids and embedded membrane proteins retain fast uniaxial diffusion � the essential requirement for obtaining spectral resolution in ssNMR of macroscopically aligned samples. The nanotube array method is applicable to lipid bilayers of essentially any composition, whereas magnetically anisotropic bicelles are only formed by certain lipids or lipid-detergent mixtures in a narrow range of molar ratios, temperature, and pH.  The unique features of lipid nanotube arrays enable studies of conformational changes of membrane proteins induced by water soluble ligands as well as various lipids.  Some of the examples of this technology include a comparison of SAMPI4 spectra of uniformly labeled Pf1 coat protein in lipid nanotube arrays composed of either pure DMPC or DOPC/DOPG (9:1 molar ratio) with spectra of the same protein in DMPC/DHPC bicelles.  Supported by DOE grant DE-FG-02-02ER153 to AIS.

Nanopore-confined lipid bilayers for structure-function studies of membrane proteins by ssNMR

245th National Meeting (2013)

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