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Data collection in protein crystallography: capillary effects and background corrections

Krieger, M. and Chambers, J. L. and Christoph, G. G. and Stroud, R. M. and Trus, B. L. (1974) Data collection in protein crystallography: capillary effects and background corrections. Acta Crystallographica. Section A, Foundations of Crystallography, 30 (6). pp. 740-748. ISSN 0108-7673. doi:10.1107/S0567739474001811.

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In protein crystallography, observed diffraction intensities must be corrected for background radiation due to scatter from air and scatter and absorption by capillary, crystal and mother liquor. A systematic study shows that a major contribution to background intensity is air scatter arising from the air intercepted by the direct X-ray beam as 'seen' by the receiving-counter aperture. As a result there is a first-order dependence of background on the 20 angle. The second-order variations in this function are principally due to absorption of the direct beam or air-scattered radiation by the capillary and to diffraction by the glass in the direct beam. To reduce data collection time and crystal exposure, individual background measurements may be approximated by interpolation from empirical background curves or, alternatively, by collecting background intensities for short times and fitting these data with a multidimensional function. If isotropic interpolation is used, i.e., if background is considered to be a function of 2θ alone, systematic errors of up to about 30% can be introduced into the interpolated backgrounds. Methods of accounting for the anisotropy in the background are derived and shown to reduce this error to 1-2%.

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Additional Information:© 1974 International Union of Crystallography. (Received 16 January 1974; accepted 24 May 1974) We thank Drs A. Kossiakoff and R. Swanson for generously supplying background data, Mr R. Almassy for helpful assistance, and Dr R. E. Marsh and Mr J. Greif for valuable discussions. We are grateful to Dr Sten Samson for allowing us to collect data on diffractometer F, a machine designed in the most part by himself, and for his supervision in the redesign of diffractometer B. We also recognize his constant attention in the redesign and improvements made to diffractometer C.
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Danforth FoundationUNSPECIFIED
NIH Postdoctoral FellowshipUNSPECIFIED
Jane Coffin Childs Memorial Fund for Medical ResearchUNSPECIFIED
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Caltech Division of Chemistry and Chemical Engineering4726
Issue or Number:6
Record Number:CaltechAUTHORS:20170317-150550734
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Official Citation:Krieger, M., Chambers, J. L., Christoph, G. G., Stroud, R. M. & Trus, B. L. (1974). Acta Cryst. A30, 740-748.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75218
Deposited By: George Porter
Deposited On:17 Mar 2017 22:54
Last Modified:15 Nov 2021 16:31

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