X-Ray Methods for Investigation of Structures of Lipid Assemblies
Published Online: 15 AUG 2009
Copyright © 2003 by Wiley-VCH Verlag GmbH & Co. KGaA. All rights reserved.
Encyclopedia of Applied Physics
How to Cite
Huang, H. W. and Yang, L. 2009. X-Ray Methods for Investigation of Structures of Lipid Assemblies. Encyclopedia of Applied Physics. .
- Published Online: 15 AUG 2009
One remarkable characteristic of lipid–water mixtures is their ability to combine in one phase a periodically ordered long-range organization in one, two, or three dimensions and a disordered short-range conformation in the unit cells. This unique property makes X-ray methods ideally suited for the structural determination of lipid assemblies. The unit cell could be a lipid bilayer or a lipidic structure that might occur during a biological process such as membrane fusion or pore formation. In this chapter, we describe methods for resolving the electron density distributions in the unit cells of various lipidic phases, including the lamellar, hexagonal, distorted hexagonal, and rhombohedral phases. The biophysical applications are to determine the structural changes caused by the inclusion of proteins to lipid bilayers. The illustrated examples include changes of the bilayer thickness, distribution of proteins or lipid components in membranes, and monolayer configurations related to membrane fusion and pore formation. The technical sections include sample preparation, diffraction geometry, data reduction, and methods for solving the phase problem, in particular a method of multiwavelength anomalous dispersion uniquely suited for solving lipidic structures.
- lipid bilayers;
- nonlamellar lipidic structures;
- phase problems;
- multiwavelength anomalous dispersion