Integrating macromolecular X-ray diffraction data with the graphical user interface iMosflm

X-ray crystallography is the predominant source of structural information for biological macromolecules, providing fundamental insights into biological function. The availability of robust and user-friendly software to process the collected X-ray diffraction images makes the technique accessible to a wider range of scientists. iMosflm/MOSFLM (http://www.mrc-lmb.cam.ac.uk/harry/imosflm) is a software package designed to achieve this goal. The graphical user interface (GUI) version of MOSFLM (called iMosflm) is designed to guide inexperienced users through the steps of data integration, while retaining powerful features for more experienced users. Images from almost all commercially available X-ray detectors can be handled using this software. Although the program uses only 2D profile fitting, it can readily integrate data collected in the 'fine phi-slicing' mode (in which the rotation angle per image is less than the crystal mosaic spread by a factor of at least 2), which is commonly used with modern very fast readout detectors. The GUI provides real-time feedback on the success of the indexing step and the progress of data processing. This feedback includes the ability to monitor detector and crystal parameter refinement and to display the average spot shape in different regions of the detector. Data scaling and merging tasks can be initiated directly from the interface. Using this protocol, a data set of 360 images with ∼2,000 reflections per image can be processed in ∼4 min.