Macromolecular cryo-crystallography

During room temperature X-ray data collection, macromolecular crystals commonly suffer severe radiation damage. Thus, diffraction data are now routinely collected with the sample held at around 100 K, significantly reducing the secondary radiation damage, and usually resulting in higher resolution and better quality data. However, at synchrotron X-ray sources, even at cryo-temperatures there has now been frequent observation of both degradation of data quality as the experiment proceeds and specific structural damage to particular amino acids due to radiation damage. Present research into cryo-techniques seeks to understand the basic physical and chemical processes involved in flash-cooling and radiation damage, to allow rational optimisation of cryo-protocols and minimisation of the deleterious effects of X-ray irradiation.