Tables for
Volume F
Crystallography of biological macromolecules
Edited by E. Arnold, D. M. Himmel and M. G. Rossmann

International Tables for Crystallography (2012). Vol. F, ch. 10.1, pp. 243-244   | 1 | 2 |

Section Annealing of biocrystals

H. Hopea* and S. Parkinb

aDepartment of Chemistry, University of California, Davis, One Shields Ave, Davis, CA 95616–5295, USA, and bDepartment of Chemistry, University of Kentucky, Lexington, Kentucky, USA
Correspondence e-mail: Annealing of biocrystals

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Prior to about 1996, it was thought that thawing of a flash-cooled crystal would inevitably lead to its demise. In spite of anecdotal evidence that some biocrystals could survive warming and re-cooling, this notion persisted until work by Harp et al. (1998)[link] and by Yeh & Hol (1998)[link] showed that some biocrystals could be annealed under certain well defined conditions. The method of Harp et al. (1998)[link] involved transfer of a flash-cooled crystal from the cold stream to a cryoprotective solution at room temperature for 3 min followed by a second flash cooling. The Yeh & Hol (1998)[link] technique, on the other hand, is performed in situ by simply blocking the cold stream for 1–2 s (i.e. until melting is observed), after which time the blockage is removed to re-cool the sample. Both these annealing protocols were shown to be capable of dramatic improvements in diffraction quality, both in terms of reduced mosaicity and improved resolution. A plausible mechanism involving the release of cooling-induced lattice stress by defect migration and solvent transport was suggested by Kriminski et al. (2002)[link]. Other work (Parkin & Hope, 2003[link]; Juers & Matthews, 2004[link]; Weik et al., 2005[link]) supports the notion of solvent transport, possibly as a result of solvent crystallization (Weik et al., 2001[link]) or other phase transition (Parkin & Hope, 2003[link]) in the aqueous regions within biocrystals.


Parkin, S. & Hope, H. (2003). Low-temperature water reconstruction in concanavalin A, with implications for controlled protein crystal annealing. Acta Cryst. D59, 2228–2236.
Harp, J. M., Timm, D. E. & Bunick, G. J. (1998). Macromolecular crystal annealing: overcoming increased mosaicity associated with cryocrystallography. Acta Cryst. D54, 622–628.
Juers, D. H. & Matthews, B. W. (2004). The role of solvent transport in cryo-annealing of macromolecular crystals. Acta Cryst. D60, 412–421.
Kriminski, S., Caylor, C. L., Nonato, M. C., Finkelstein, K. D. & Thorne, R. E. (2002). Flash-cooling and annealing of protein crystals. Acta Cryst. D58, 459–471.
Weik, M., Kryger, G., Schreurs, A. M. M., Bouma, B., Silman, I., Sussman, J. L., Gros, P. & Kroon, J. (2001). Solvent behaviour in flash-cooled protein crystals at cryogenic temperatures. Acta Cryst. D57, 566–573.
Weik, M., Schreurs, A. M. M., Leiros, H.-K. S., Zaccai, G., Ravelli, R. B. G. & Gros, P. (2005). Supercooled liquid-like solvent in trypsin crystals: implications for crystal annealing and temperature-controlled X-ray radiation damage studies. J. Synchrotron Rad. 12, 310–317.
Yeh, J. I. & Hol, W. G. J. (1998). A flash-annealing technique to improve diffraction limits and lower mosaicity in crystals of glycerol kinase. Acta Cryst. D54, 479–480.

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