Lanthanide ion assisted magnetic alignment of model membranes and macromolecules

Orientational and structural properties of membrane peptides and membrane proteins are frequently studied using solid state NMR techniques with aligned samples. Depending on the size of the protein under study, one may choose to employ bicelle or lanthanide-doped bilayer systems, which are known to spontaneously align in magnetic fields with the symmetry axes perpendicular or parallel to the magnetic field, respectively. Using an order matrix formalism, a brief description is given of the anisotropic interactions which are utilized to determine orientational and structural properties of membrane associated macromolecules. The phenomenon of magnetic alignment in these systems is reviewed with particular attention to lanthanide ion assisted alignment. Finally, several examples of lanthanide ion assisted magnetic alignment of macromolecules for high-resolution solution NMR applications are discussed.