X-ray diffraction experiment--the last experiment in the structure elucidation process.

Recent years have brought not only an avalanche of new macromolecular structures, but also significant advances in the protein structure determination methodology only now making its way into structure-based drug discovery. In this chapter, we review recent methodology developments in X-ray diffraction experiments that led to fast and very accurate elucidation of three-dimensional structures of macromolecules. We will discuss the role of data collection as the last experiment performed in the crystal structure determination process. A statistical analysis of diffraction experiments that are reported in the Protein Data Bank (PDB) is also presented.