Powder diffraction studies on proteins: An overview of data collection approaches

Following the seminal work of Von Dreele, high quality powder X-ray diffraction studies on proteins are being established as a valuable complernentary technique to singlecrystal measurements. Several studies using a variety of experiments approaches have been reported in the literature, including high-resolution studies employing parallel beam geornetry and high intensity measurements using position sensitive detectors. Tile choice of the optimum instrumental configuration depends on a number of competing factors such as the amount of sample available, its radiation sensitivity, and the quality of the data required for data analysis, e.g. angular resolution, the extent of the data in d-spacing, or the number of patterns required to explore the protein's behaviour at different temperatures, or under different crystallisation conditions, etc. Here we discuss several advantages and disadvantages of different data collection methods followed for selected examples of small proteins.