Figure 3
The correct choice of protein crystal sample size is important for freezing. Diffraction pattern (a) involved too big a crystal (0.5–0.8 mm in size, minimum to maximum) and yielded high mosaicity and split spots. In (b), sharp single spots (not split) from a crystal of size 0.2 mm are shown and from which a full data set could be recorded and processed to 1.2 Å. Sample: disaccharide-bound concanavalin A (see Sanders et al., 2001 ). Methods to reach atomic resolution but at room temperature, which is, after all, closer to physiological temperature, seek to improve the reflection peak-to-background ratio by combining the synchrotron radiation beam near parallel collination with low-mosaicity crystals (Snell et al., 1999 ). Hence, the link between crystal growth, data collection and structural detail is made (Boggon et al., 2000 ). One can readily see how high-brilliance synchrotron radiation X-ray sources and their gradual evolution over these last 20 years (Ealick & Helliwell, 1999 , and articles therein) has had such a profound effect on the data-collection capability in protein crystallography structural studies. |