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

International Tables for Crystallography (2006). Vol. F, ch. 19.2, p. 424   | 1 | 2 |

Section 19.2.3.2. Radiation damage

W. Chiua*

aVerna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
Correspondence e-mail: wah@bcm.tmc.edu

19.2.3.2. Radiation damage

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All protein crystals are prone to radiation damage caused by inelastically scattered electrons (Glaeser, 1971[link]). This physical process is easily seen in the fading of electron diffraction intensities of a protein crystal as the accumulated doses increase. The consequence of damage is a preferential loss of the high-resolution information. Radiation damage is a dose-dependent process and cannot be reduced by adjusting the dose rate (flux) of the irradiating electrons. The strategy used to minimize the damage is to record the diffraction or image data from a specimen area that has not been previously exposed to electrons for purposes of focusing or other adjustments (Unwin & Henderson, 1975[link]). This is called a minimal or low-dose procedure. In addition, keeping a specimen at low temperature (<113 K) allows it to tolerate a higher radiation dose (by a factor of about 4 to 6) before reaching the same extent of damage as at room temperature (Hayward & Glaeser, 1979[link]). It has been shown that damage reduction is minimal below liquid-nitrogen temperature (Chiu et al., 1981[link]). However, there have been some impressive results using the electron cryomicroscope to study membrane protein crystals kept at liquid-helium temperature (4 K) (Kühlbrandt et al., 1994[link]; Kimura et al., 1997[link]; Miyazawa et al., 1999[link]).

References

Chiu, W., Knapek, E., Jeng, T. W. & Dietrick, I. (1981). Electron radiation damage of a thin protein crystal at 4 K. Ultramicroscopy, 6, 291–296.Google Scholar
Glaeser, R. M. (1971). Limitations to significant information in biological electron microscopy as a result of radiation damage. J. Ultrastruct. Res. 36, 466–482.Google Scholar
Hayward, S. B. & Glaeser, R. M. (1979). Radiation damage of purple membrane at low temperature. Ultramicroscopy, 4, 201–210.Google Scholar
Kimura, Y., Vassylyev, D. G., Miyazawa, A., Kidera, A., Matsushima, M., Mitsuoka, K., Murata, K., Hirai, T. & Fujiyoshi, Y. (1997). Surface of bacteriorhodopsin revealed by high-resolution electron crystallography. Nature (London), 389, 206–211.Google Scholar
Kühlbrandt, W., Wang, D. N. & Fujiyoshi, Y. (1994). Atomic model of plant light-harvesting complex by electron crystallography. Nature (London), 367, 614–621.Google Scholar
Miyazawa, A., Fujiyoshi, Y., Stowell, M. & Unwin, N. (1999). Nicotinic acetylcholine receptor at 4.6 Å resolution: transverse tunnels in the channel wall. J. Mol. Biol. 288, 765–786.Google Scholar
Unwin, P. N. & Henderson, R. (1975). Molecular structure determination by electron microscopy of unstained crystalline specimens. J. Mol. Biol. 94, 425–440.Google Scholar








































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