Protein crystal perfection and its application

Knowledge of protein crystal perfection in theory and practice is reviewed. X-ray methods of assessing perfection such as mosaicity, topography and reciprocal-space mapping are described. X-ray diffraction physics applications of protein crystals such as in Laue geometry, the large-angle oscillation technique and forming polychromatic profiles across diffraction spots are covered. Cryo- and room-temperature cases are discussed including in X-ray and neutron protein crystallography. Experience of freezing very large crystals, which are commonly used today in neutron protein crystallography, is highlighted.