Supramolecular protein structure determination by site-specific long-range intermolecular solid state NMR spectroscopy.

We demonstrate that 3D Z-filtered TEDOR experiments, when performed on mixtures of isotopically labeled protein samples, report on site-specific intermolecular distance restraints. These data sets can be leveraged to perform rigorous structure calculations of the protein interface. In the example demonstrated here, we determine the packing arrangement of our nanocrystalline GB1 preparation to be consistent with the trigonal form as determined by X-ray diffraction. This represents an important proof of principle, in a case where the results can be directly compared with other structural information. We envision the application of this approach to determining the registry and quaternary arrangement of protein fibrils, which most often cannot be determined by diffraction methods.