²H, ¹⁵N and ³¹P solid-state NMR spectroscopy of polypeptides reconstituted into oriented phospholipid membranes

Abstract

Although membrane proteins are abundant and fulfill many important functions, only a few high-resolution conformations of this class of proteins have been published (reviewed in [1; 2]). Structural investigations are hampered by the problems that are encountered during their large-scale expression and purification as well as during application of diffraction and NMR techniques. Since publication of the high-resolution diffraction map of the photoreaction centre [3], the conformations of other bacterial membrane proteins have been solved at a relatively slow pace. Most of these proteins already occur at high concentrations in nature and some of them even in ordered arrays [1; 2]. More recently high resolution structures of eukaryotic membrane proteins have been added to the structural data base, including rhodopsin, a G protein-coupled receptor [4; 5]. Improvements in crystallisation as well as in X-ray and electron diffraction techniques hold promise that these developments will accelerate, and structures of an increasing number of membrane proteins will become available in the future. Some of this work illuminates structural changes that occur during functional activities in a stroboscopic manner [4; 6].