title: Zero-dose extrapolation as part of macromolecular synchrotron data reduction.
abstract: Radiation damage to macromolecular crystals at third-generation synchrotron sites constitutes a major source of systematic error in X-ray data collection. Here, a computational method to partially correct the observed intensities during data reduction is described and investigated. The method consists of a redundancy-based zero-dose extrapolation of a decay function that is fitted to the intensities of all observations of a unique reflection as a function of dose. It is shown in a test case with weak anomalous signal that this conceptually simple correction, when applied to each unique reflection, can significantly improve the accuracy of averaged intensities and single-wavelength anomalous dispersion phases and leads to enhanced experimental electron-density maps. Limitations of and possible improvements to the method are discussed.
authors.affiliation: Fachbereich Biologie, Universität Konstanz, D-78457 Konstanz, Germany. kay.diederichs@uni-konstanz.de
authors.forename: Kay
authors.initials: K
authors.lastname: Diederichs
authors.forename: Sean
authors.initials: S
authors.lastname: McSweeney
authors.forename: Raimond B G
authors.initials: RB
authors.lastname: Ravelli
mesh_terms: D000465:Algorithms; D018360:Crystallography, X-Ray / Q000706:statistics & numerical data*; D003627:Data Interpretation, Statistical; D046911:Macromolecular Substances; D008958:Models, Molecular; D012984:Software; D055672:Static Electricity; D013223:Statistics as Topic / Q000379:methods; D017356:Synchrotrons
chemical_list: D046911:Macromolecular Substances