International
Tables for
Crystallography
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. 9.1, pp. 212-213   | 1 | 2 |

Section 9.1.5. Goniostat geometry

Z. Dautera* and K. S. Wilsonb

aNCI Frederick & Argonne National Laboratory, Building 202, Argonne, IL 60439, USA, and bYork Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, England
Correspondence e-mail:  dauter@anl.gov

9.1.5. Goniostat geometry

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9.1.5.1. Overview

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The diffraction condition for a particular reflection is fulfilled when the corresponding reciprocal-lattice point lies on the surface of the Ewald sphere. If a stationary crystal is irradiated by the X-ray beam, only a few reflections will lie in the diffracting position. To record intensities of a larger number of reflections, either the size of the Ewald sphere or the crystal orientation has to be changed. The first option, with the use of non-monochromatic, or `white', radiation, is the basis of the Laue method (Chapter 8.2[link] ). If the radiation is monochromatic, i.e. single-wavelength, the crystal has to be rotated during exposure to bring successive reflections into the diffraction condition.

9.1.5.2. The screenless rotation method and 2D detectors

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In the early days of protein crystallography, a number of geometries were used for X-ray cameras, notably the Weissenberg and precession methods. In addition, single-counter diffractometers were used with four-circle goniostats. However, in practice only the screenless rotation geometry (Arndt & Wonacott, 1977[link]) survives today. This requires a 2D detector, which was initially in the form of photographic film. It is of significance that typical film sizes were of the order of 10 × 10 cm with up to 2000 × 2000 scanned pixels; a similar effective area has proved effective for image plates and charge-coupled devices (CCDs).

However, automation of protein-data collection needed efficient 2D detectors (Part 7[link] ). The first were multiwire proportional counters, which found widespread use in the early 1980s (Hamlin, 1985[link]). These finally proved to be limited by a combination of spatial resolution and dead time of the read-out. A major advance occurred in the late 1980s with the widespread introduction of imaging plates (Amemiya, 1995[link]), scanned on-line both at synchrotron beamlines and on laboratory rotating-anode sources. This represented a revolution in macromolecular data collection, making it technically straightforward to save full 2D images with sufficient positional resolution and dynamic range to computer disk automatically. The limiting factor of the imaging plate proved to be the slow read-out time of the order of several seconds to minutes. At high-intensity sources in particular, e.g. third-generation SR sites, exposure times per image can fall to one second or less, and with an imaging plate the bulk of the time is spent reading the detector image rather than collecting data. Typical data-collection times with imaging plates remained of the order of several hours, even with the use of SR. This is a much smaller problem with rotating-anode sources, where exposure times dominate the duty cycle.

For high-intensity SR sites, the detector of choice is the CCD (Gruner & Ealick, 1995[link]). The spatial resolution is comparable with that of imaging plates, but the read-out time can be as low as one to two seconds. This means that complete data can be recorded in minutes rather than hours and has transformed approaches to data collection.

While the CCD has revolutionized data-collection times, further advances are expected from the use of solid-state pixel detectors. Such detectors record individual X-ray quanta and have essentially zero read-out time. The most advanced of these, the PILATUS 1M device, is a hybrid pixel array detector (Broennimann et al., 2006[link]; Hülsen et al., 2006[link]), first installed at the Swiss Light Source.

Almost all current 2D detectors are used in conjunction with a goniostat, providing rotation of the crystal about a single axis during exposure. Indeed, the majority of instruments have only a single rotation axis. The remainder are based on the kappa (ω, κ, ϕ) cradle to select different initial orientations of the sample in the beam; the sample is nevertheless subsequently rotated about a single axis for data collection.

References

Amemiya, Y. (1995). Imaging plates for use with synchrotron radiation. J. Synchrotron Rad. 2, 13–21.
Arndt, U. W. & Wonacott, A. J. (1977). Editors. The Rotation Method in Crystallography. Amsterdam: North Holland.
Broennimann, Ch., Eikenberry, E. F., Henrich, B., Horisberger, R., Huelsen, G., Pohl, E., Schmitt, B., Schulze-Briese, C., Suzuki, M., Tomizaki, T., Toyokawa, H. & Wagner, A. (2006). The PILATUS 1M detector. J. Synchrotron Rad. 13, 120–130.
Gruner, S. M. & Ealick, S. E. (1995). Charge coupled device X-ray detectors for macromolecular crystallography. Structure, 3, 13–15.
Hamlin, R. (1985). Multiwire area X-ray diffractometers. Methods Enzymol. 114, 416–452.
Hülsen, G., Broennimann, C., Eikenberry, E. F. & Wagner, A. (2006). Protein crystallography with a novel large-area pixel detector. J. Appl. Cryst. 39, 550–557.








































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