Interpreting solution X-ray scattering data using molecular simulations

Small-angle and wide-angle X-ray scattering in solution (SAXS, WAXS, SWAXS) is an increasingly accurate method for obtaining information on biomolecular structures, ensembles, and time-resolved dynamics at near-native conditions. However, the interpretation of the solution scattering data by computational methods is complicated by the low information content of the data, by scattering contributions from the hydration layer, and by unknown systematic errors. In the light of available computational methods, we first review the main computational challenges with the interpretation of SWAXS data. Molecular dynamics (MD) simulations may help to overcome these challenges and guide the interpretation of SWAXS in multiple ways. The physical information in atomistic force fields complements the low-information SWAXS data; explicit-solvent MD may be used to predict solvent scattering, and the MD-related sampling methods may guide the structure refinement against SWAXS data.