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Proceedings Paper

Phase retrieval in nanocrystallography
Author(s): Joe P. J. Chen; John C. H. Spence; Rick P. Millane
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Paper Abstract

Protein X-ray crystallography is a method for determining the three-dimensional structures of large biological molecules by analysing the amplitudes of X-rays scattered from a crystalline specimen of the molecule under study. Conventional structure determination in protein crystallography requires chemical modification to the sample and collection of additional data in order to solve the corresponding phase problem. There is an urgent need for a direct (digital) low-resolution phasing method that does not require modified specimens. Whereas diffraction from large crystals corresponds to samples (so-called Bragg samples) of the amplitude of the Fourier transform of the scattering density, the diffraction from very small crystals allows measurement of the diffraction amplitude between the Bragg samples. Although highly attenuated, these additional measurements offer the possibility of iterative phase retrieval without the use of ancillary experimental data. In this study we examine the noise characteristics of small-crystal diffraction and propose a data selection strategy to improve the quality of reconstructions using iterative phase retrieval algorithms. Simulation results verify that a higher noise level can be tolerated by using such a data selection strategy.

Paper Details

Date Published: 19 October 2012
PDF: 12 pages
Proc. SPIE 8500, Image Reconstruction from Incomplete Data VII, 85000I (19 October 2012); doi: 10.1117/12.930930
Show Author Affiliations
Joe P. J. Chen, Univ. of Canterbury (New Zealand)
John C. H. Spence, Arizona State Univ. (United States)
Rick P. Millane, Univ. of Canterbury (New Zealand)

Published in SPIE Proceedings Vol. 8500:
Image Reconstruction from Incomplete Data VII
Philip J. Bones; Michael A. Fiddy; Rick P. Millane, Editor(s)

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