Abstract
Neutron crystallography is a powerful technique for directly visualizing the locations of H atoms in biological macromolecules. This information has provided key new insights into enzyme mechanisms, ligand binding and hydration. However, despite the importance of this information, the application of neutron crystallography in biology has been limited by the relatively low flux of available neutron beams and the large incoherent neutron scattering from hydrogen, both of which contribute to weak diffraction data with relatively low signal-to-background ratios. A method has been developed to fit weak data based on three-dimensional profile fitting of Bragg peaks in reciprocal space by an Ikeda–Carpenter function with a bivariate Gaussian. When applied to data collected from three different proteins, three-dimensional profile fitting yields intensities with higher correlation coefficients (CC1/2) at high resolutions, decreased Rfree factors, extended resolutions and improved nuclear density maps. Importantly, additional features are revealed in nuclear density maps that may provide additional scientific information. These results suggest that three-dimensional profile fitting will help to extend the capabilities of neutron macromolecular crystallography.
Original language | English |
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Pages (from-to) | 1085-1095 |
Number of pages | 11 |
Journal | Acta Crystallographica Section D: Structural Biology |
Volume | 74 |
Issue number | 11 |
DOIs | |
State | Published - Nov 2018 |
Funding
This work was funded through grant R01-GM071939 from the National Institutes of Health. The neutron scattering measurements were carried out at the Spallation Neutron Source, which is sponsored by the Division of Scientific User Facilities, Office of Basic Energy Sciences, US Department of Energy under contract No. DE-AC05-00OR22725 with UT-Battelle LLC. This research was also sponsored by the Applied Mathematics Division of ASCR, DOE, in particular under the ACUMEN project. Production and crystallization of PsbO was funded by Deutsche Forschungsgemeinschaft (DFG) grant SFB1078, TP A5. This work used samples grown at Oak Ridge National Laboratory’s Center for Structural and Molecular Biology (CSMB), which is funded by the Office of Biological Environment Research in the Department of Energy’s Office of Science.
Keywords
- integration
- neutron crystallography
- profile fitting