Improved fitting of solution X-ray scattering data to macromolecular structures and structural ensembles by explicit water modeling.
A new procedure, AXES, is introduced for fitting small-angle X-ray scattering (SAXS) data to macromolecular structures and ensembles of structures. By using explicit water models to account for the effect of solvent, and by restricting the adjustable fitting parameters to those that dominate experimental uncertainties, including sample/buffer rescaling, detector dark current, and, within a narrow range, hydration layer density, superior fits between experimental high resolution structures and SAXS data are obtained. AXES results are found to be more discriminating than standard Crysol fitting of SAXS data when evaluating poorly or incorrectly modeled protein structures. AXES results for ensembles of structures previously generated for ubiquitin show improved fits over fitting of the individual members of these ensembles, indicating these ensembles capture the dynamic behavior of proteins in solution.
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. AlexanderG@intra.niddk.nih.gov
Alexander
A
Grishaev
Liang
L
Guo
Thomas
T
Irving
Ad
A
Bax
D046911:Macromolecular Substances / Q000737:chemistry*; D008958:Models, Molecular; D053838:Scattering, Small Angle; D014867:Water / Q000737:chemistry*; D014965:X-Rays
D046911:Macromolecular Substances; D014867:Water