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

© International Union of Crystallography 2006
International Tables for Crystallography (2006). Vol. F. ch. 19.5, pp. 446-447   | 1 | 2 |

Section 19.5.6.3. Background subtraction

R. Chandrasekarana* and G. Stubbsb

aWhistler Center for Carbohydrate Research, Purdue University, West Lafayette, IN 47907, USA, and  bDepartment of Molecular Biology, Vanderbilt University, Nashville, TN 37235, USA
Correspondence e-mail:  chandra@purdue.edu

19.5.6.3. Background subtraction

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The background can be very high in fibre-diffraction data because of long exposure times and scattering from amorphous material. Because of specimen disorientation, fibre-diffraction data often contain large regions where there is no space between layer lines, so local-background-fitting methods are rarely useful. The background may be determined by fitting an analytical function to intensities at points between reflections (Millane & Arnott, 1985[link]; Lorenz & Holmes, 1993[link]), or by fitting a function that includes both signal and background components to the reflection data. This type of profile fitting has been described for individual reflections (Fraser et al., 1976[link]), for data in concentric rings about the centre of the diffraction pattern (Makowski, 1978[link]) and for entire data sets (Yamashita et al., 1995[link]; Ivanova & Makowski, 1998[link]).

References

First citation Fraser, R. D. B., MacRae, T. P., Miller, A. & Rowlands, R. J. (1976). Digital processing of fibre diffraction patterns. J. Appl. Cryst. 9, 81–94.Google Scholar
 First citation Ivanova, M. I. & Makowski, L. (1998). Iterative low-pass filtering for estimation of the background in fiber diffraction patterns. Acta Cryst. A54, 626–631.Google Scholar
 First citation Lorenz, M. & Holmes, K. C. (1993). Computer processing and analysis of X-ray fiber diffraction data. J. Appl. Cryst. 26, 82–91.Google Scholar
 First citation Makowski, L. (1978). Processing of X-ray diffraction data from partially oriented specimens. J. Appl. Cryst. 11, 273–283.Google Scholar
 First citation Millane, R. P. & Arnott, S. (1985). Background removal in X-ray fiber diffraction patterns. J. Appl. Cryst. 18, 419–423.Google Scholar
 First citation Yamashita, I., Vonderviszt, F., Mimori, Y., Suzuki, H., Oosawa, K. & Namba, K. (1995). Radial mass analysis of the flagellar filament of Salmonella: implications for the subunit folding. J. Mol. Biol. 253, 547–558.Google Scholar








































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