The conformational ensemble of an intrinsically disordered protein explains peak shapes under DNP conditions

Elucidating the conformational preferences of regions of intrinsic disorder in biologically relevant contexts represents a frontier of structural biology. The sensitivity enhancements conferred by DNP enable structural studies of proteins in native contexts by MAS NMR. However, DNP requires low temperatures which results in broad peaks, particularly for for regions of intrinsic disorder. We describe an approach to predict and interpret peak shapes for frozen regions of intrinsic disorder in terms of dihedral angle populations. We demonstrate the method using the protein a-synuclein. This approach can be used to obtain experimental structural restraints for regions of intrinsic disorder in both simplified and biological settings, providing information that eludes characterization by diffraction-based methods as well as solution-state NMR spectroscopy and molecular dynamics due to molecular size limitations. ### Competing Interest Statement The authors have declared no competing interest. * NMR : nuclear magnetic resonance MAS : magic angle spinning DNP : dynamic nuclear polarization IDR : intrinsically disordered region MD : molecular dynamics.