Neutron and x-ray scattering from isotropic and aligned membranes

Neutron and X‐ray scattering are two of the most powerful structural determination techniques presently available. Although many are familiar with the exploits of atomic resolution X‐ray crystallography—in particular, protein crystallography—these techniques also have applications in polymer science, colloid chemistry, and materials science. With regard to structural biology, the various neutron and X‐ray scattering techniques complement crystallographic studies that require hard‐to‐obtain high quality crystals of macromolecules. In biological systems, plasma membranes surround cells and function as an interface between the cell's interior and exterior environments. Phospholipids, cholesterol, and a variety of integral and peripheral proteins are the chief components of these membranes. When compared to powder or liposomal preparations, aligned membranes have allowed a variety of techniques of extracting unambiguous structural information. With regard to scattering, because the signal is not isotropic, as is the case for liposomal preparations, aligned samples permit clear differentiation between in‐plane and out‐of‐plane structures.