Open AccessModelling and refining site‐specific radiation damage in SAD/MAD phasing
Author(s) -
Schiltz M.,
Bricogne G.
Publication year - 2007
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049506038970
Subject(s) - radiation damage , radiation , phaser , scattering , optics , anomalous scattering , reflection (computer programming) , diffraction , physics , irradiation , computational physics , computer science , nuclear physics , programming language
Site‐specific radiation damage on anomalously scattering sites can be used to generate additional phase information in standard single‐ or multi‐wavelength anomalous diffraction (SAD or MAD) experiments. In this approach the data are kept unmerged, down to the Harker construction, and the evolution of site‐specific radiation damage as a function of X‐ray irradiation is explicitly modelled and refined in real space. Phasing power is generated through the intensity differences of symmetry‐related reflections or repeated measurements of the same reflection recorded at different X‐ray doses. In the present communication the fundamentals of this approach are reviewed and different models for the description of site‐specific radiation damage are presented. It is shown that, in more difficult situations, overall radiation damage may unfold on a time scale that is similar to the evolution of site‐specific radiation damage or to the total time that is required to record a complete data set. In such cases the quality of the phases will ultimately be limited by the effects of overall radiation damage.