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. 7.2, p. 152   | 1 | 2 |

Section 7.2.5. Applications to macromolecular crystallography

M. W. Tate,a* E. F. Eikenberryb and S. M. Grunera

aDepartment of Physics, 162 Clark Hall, Cornell University, Ithaca, NY 14853-2501, USA, and  bSwiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
Correspondence e-mail:  mwt5@.cornell.edu

7.2.5. Applications to macromolecular crystallography

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Storage rings. CCD detectors have gained widespread acceptance for macromolecular crystallography at storage-ring sources, in part because of the high-quality data they give, but more for their speed, convenience and efficiency. Accurate data to high resolution are especially important for MAD phasing, and CCD detectors excel in this application. In the past with film, or even storage phosphors, teams of perhaps ten people were required to perform a synchrotron experiment; today, a single person per shift can perform an experiment. With increasing beam flux, improved X-ray optics and faster CCDs, it is often possible to collect full data sets in little more than an hour. Anticipated improvements in speed for CCD detectors should soon make it feasible to collect fine-sliced rotation data routinely; these data are expected to yield better structure solutions.

Home laboratories. Acceptance of CCD detectors for macromolecular crystallography at home laboratories has been slower, in part because there is not such a premium on speed, and in part because of cost. Diffracted spot sizes are larger than at synchrotrons, so highly accurate data should be obtainable. Fully automatic storage phosphor systems work quite well with conventional sources and at this time are lower in cost than large CCD detectors. However, they have a minimum cycle time, caused by the mechanics of the readout scheme, and the required exposure for a strongly diffracting crystal can best this time by a wide margin. Thus, for strongly diffracting specimens, CCD detectors can be significantly more efficient.








































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