Cryocooling and radiation damage in macromolecular crystallography

Abstract

Advances in cryocrystallographic techniques for macromolecular crystallography have been intimately intertwined with efforts to reduce the deleterious effects of X-ray damage inflicted during the collection of diffraction data. A brief overview of cryomethods and their rationale is given. This is followed by a summary of our current limited understanding of radiation damage in cryocooled crystals, investigations aimed at minimizing its effects and finally some developments which actually utilize it both for phasing and to extend structural knowledge.

Progress in rational methods of cryoprotection in macromolecular crystallography

“…Larger molecules, such as high-molecular-weight PEGs, are less able to penetrate the solvent channels and often require an additional cryoprotective agent, such as a low-molecular-weight PEG. Further discussion of this topic can be found in some recent reviews (Garman, 1999;Garman & Owen, 2006). 4.3.3.…”

“…However, it is common for the cooling process to disrupt the crystal order and decrease the diffraction quality. To address this problem, the crystal is often treated with a cryoprotective solution prior to cooling (Haas & Rossmann, 1970;Hope, 1988;Henderson, 1990;Rodgers, 1994;Garman & Schneider, 1997;Schneider, 1997;Garman, 1999Garman, , 2003Kriminski et al, 2002;Juers & Matthews, 2004b;Garman & Owen, 2006). Finding the optimal cryoprotective conditions is largely dependent on the crystal system and often involves substantial screening.…”

Temperature-dependent macromolecular X-ray crystallography

“…Macromolecular X-ray crystallography has greatly benefited from several innovations at the end of the last century, including the implementation of cryo-methods (Hope, 1990;Teng, 1990;Garman & Schneider, 1997;Garman & Owen, 2006) and the availability of brilliant X-ray beams from thirdgeneration synchrotron sources. The timing was fortuitous, since the widespread use of the latter would not have been possible without the former.…”

Monitoring Structural Transformations in Crystals. Part 15. Structural Changes in Crystals Caused by UV Radiation Despite the Lack of a Photochemical Reaction

“…It should be also said that a phenomenon of an increase of cell constants caused by electromagnetic radiation is known in the crystallographic literature concerning radiation damage, however, in the case of use of X-rays [13][14][15][16][17][18][19][20] and not for UV radiation. An increase of a cell volume resulting from X-rays damages was described in the last decade mainly for crystals of macromolecules.…”

“…X-ray structure analysis has also helped to monitor the decrease of crystal diffracting power caused by X-rays [13][14][15][16][17][18][19][20] (crystal damage by bright X-ray beams is a serious problem in crystallographic studies of macromolecules [14][15][16][17][18][19][20]). However, monitoring crystal damages caused by UV radiation has been extremely rare [21].…”