Abstract
This chapter discusses consumer's guide to protein crystallography. The atomic structures of large and small molecules can be determined by a technique called X-ray diffraction provided the molecule in question can be crystallized. Most of the three-dimensional structures of proteins, nucleic acids, and viruses that are known at present have been determined by X-ray crystallography. In favorable cases, the resolution of a crystallographic structure determination is such that the relative positions of all non-hydrogen atoms are known to a precision of a few tenths of an angstrom unit. There are two reasons for a non-specialist care about the details of this technique: first, the demand for structural information is so intense, and the competition to publish structures first has become so keen, that premature structure, incorrect in whole or in part, has appeared in the literature. Some of these have even found their way into the Protein Data Bank, the repository for protein three-dimensional structural information maintained at the Brookhaven National Laboratory. Second, structural information has become so central to enzymology, cell biology, and immunology that many people in those fields are likely to be involved in collaboration with a protein crystallographer at some point in their careers. The chapter focuses to teach this basic information.