Direct phasing of nanocrystal diffraction.

IF 1.8 4区材料科学

Acta Crystallographica Section A Pub Date : 2013-11-01 Epub Date: 2013-10-05 DOI:10.1107/S0108767313023362

Veit Elser

引用次数: 27

Abstract

Recent experiments at free-electron laser X-ray sources have been able to resolve the intensity distributions about Bragg peaks in nanocrystals of large biomolecules. Information derived from small shifts in the peak positions augment the Bragg samples of the particle intensity with samples of its gradients. Working on the assumption that the nanocrystal is entirely generated by lattice translations of a particle, an algorithm is developed that reconstructs the particle from intensities and intensity gradients. Unlike traditional direct phasing methods that require very high resolution data in order to exploit sparsity of the electron density, this method imposes no constraints on the contrast other than positivity and works well at low resolution. Successful reconstructions are demonstrated with simulated P1 lysozyme nanocrystal data down to a signal-to-noise ratio of 2 in the intensity gradients.

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纳米晶衍射的直接相位。

最近在自由电子激光x射线源上的实验已经能够解析出大分子纳米晶体中布拉格峰的强度分布。从峰值位置的小位移中获得的信息用其梯度的样本增加了粒子强度的布拉格样本。在假设纳米晶体完全由粒子的晶格平移产生的基础上，开发了一种从强度和强度梯度重建粒子的算法。传统的直接相位方法需要非常高的分辨率数据来利用电子密度的稀疏性，而这种方法不像传统的方法那样对对比度施加任何限制，除了正性，并且在低分辨率下也能很好地工作。通过模拟P1溶菌酶纳米晶体数据，在强度梯度下的信噪比为2，成功地进行了重建。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Acta Crystallographica Section A 化学-晶体学

自引率

11.10%

发文量

审稿时长

3 months

期刊介绍： Acta Crystallographica Section A: Foundations and Advances publishes articles reporting advances in the theory and practice of all areas of crystallography in the broadest sense. As well as traditional crystallography, this includes nanocrystals, metacrystals, amorphous materials, quasicrystals, synchrotron and XFEL studies, coherent scattering, diffraction imaging, time-resolved studies and the structure of strain and defects in materials. The journal has two parts, a rapid-publication Advances section and the traditional Foundations section. Articles for the Advances section are of particularly high value and impact. They receive expedited treatment and may be highlighted by an accompanying scientific commentary article and a press release. Further details are given in the November 2013 Editorial. The central themes of the journal are, on the one hand, experimental and theoretical studies of the properties and arrangements of atoms, ions and molecules in condensed matter, periodic, quasiperiodic or amorphous, ideal or real, and, on the other, the theoretical and experimental aspects of the various methods to determine these properties and arrangements.