CHAPTER 4: Demonstration of the Equivalence of Solid-State NMR Orientational Constraints from Magnetic and Rotational Alignment of the Coat Protein in a Filamentous Bacteriophage

Structures of protein subunits of supramolecular assemblies can be determined from the orientations of bonds relative to an axis collinear with a stationary magnetic field or an axis about which rotational diffusion occurs, such as the length of a rod-shaped particle. As an example, here we demonstrate that equivalent angular constraints can be measured from solid-state NMR spectra of the filamentous bacteriophage fd whether made from oriented samples that are stationary or unoriented samples undergoing magic angle spinning as long as uniaxial rotational diffusion along the long axis of the virus particles is present. This is a general NMR approach and is applicable to other biological supramolecular assemblies such as membranes.