In Crystallographic Methods and Protocols leading specialists in the application of X-ray crystallography to biological problems provide a basic and comprehensive guide to its successful use in obtaining detailed three-dimensional structures of proteins, nucleic acids, and their complexes. These deeply experienced researchers describe in clear practical terms their proven methods for preparing samples, crystallizing them, obtaining preliminary characterizations, acquiring and analyzing data, and solving and refining structures. Their step-by-step instructions give biologically trained workers immediate access to a powerful technique essential to solving many biologically relevant problems.