Cryo-cooling in macromolecular crystallography: advantages, disadvantages and optimization

The flash-cooling of crystals in macromolecular crystallography has become commonplace. The procedure makes it possible to collect data from much smaller specimens than was the case in the past. Also, flash-cooled crystals are much less prone to radiation damage than their room-temperature counterparts, allowing data to be accumulated over extended periods of time. Notwithstanding the attractiveness of the technique, it does have potential disadvantages. First, better methods need to be developed to prevent damage to crystals on freezing. There is also a risk that structures determined at low temperature may suggest conclusions based on aspects of the structure that are not necessarily relevant at room temperature.