MACROSCOPIC ORIENTATION OF NATURAL AND MODEL MEMBRANES FOR STRUCTURALSTUDIES

One approach for obtaining high-resolution structural and functional i nformation for biomembranes and their proteins is by static solid-stat e NMR of oriented systems. Here, a general procedure to align fully fu nctional biological membranes containing large membrane proteins (M-r >30,000) is described. The method, based on the isopotential spin-dry ultracentrifugation technique, relies on the centrifugation of membran e fragments onto a support with simultaneous, or subsequent, partial e vaporation of the solvent which aids alignment. The quality of orienta tion, as shown by the mosaic spread of the samples, was monitored by s tatic solid-state P-31 NMR for the phospholipids and by H-2 NMR for a deuterated retinal in bovine rhodopsin. The generality of this method is demonstrated with three different membranes containing bo vine rhod opsin in reconstituted bilayers, natural membranes with the red cell a nion exchange transport protein in erythrocytes, band 3, and the nicot inic acetylcholine receptor, (C) 1997 Academic Press.