Modern Methods for Rapid X-Ray Diffraction Data Collection from Crystals of Macromolecules

During the last 8 years, there has been a revolution in X-ray crystallographic data-collection technology, resulting in an enormous increase in data-acquisition rates and in the range of macromolecules that can be investigated in most laboratories. Provided that the macromolecule forms crystals of reasonable size (minimum of 100 �m in the largest dimension for in-house experiments) and quality, the next step in the determination of its three-dimensional structure is to collect X-ray diffraction data. Some fairly sophisticated equipment is required for this: an X-ray generator, an X-ray detector, and a system of stepping motors (“a goniometer”) with translational slides and rotational arcs above them (“goniometer head”) on which the crystal in a glass or quartz capillary tube is usually held using plasticene and then aligned in the X-ray beam. This chapter will outline the principles of the most commonly used laboratory equipment, and give the basic steps involved in data collection and processing.