Structure determination of protein-protein complexes with long-range anisotropic paramagnetic NMR restraints

Paramagnetic NMR spectroscopy has evolved rapidly in the last decade, and has shown to be a very useful tool for solving structures of protein-protein complexes. A major breakthrough has been the development of paramagnetic metal binding tags that can be attached specifically to the protein. These tags have greatly facilitated the use of anisotropic paramagnetic restraints such as pseudocontact shifts and residual dipolar couplings arising from paramagnetic self-alignment. Such restraints are particularly useful for the study of large protein complexes. This review focuses on the recent developments in structural characterization of protein-protein complexes using anisotropic paramagnetic NMR restraints.