A statistic for local intensity differences: robustness to anisotropy and pseudo-centering and utility for detecting twinning
A statistic for local intensity differences: robustness to anisotropy and pseudo-centering and utility for detecting twinning
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DOI：
10.1107/s0907444903007947
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发表时间：
2003-07-01
期刊：
影响因子：
--
通讯作者：
Yeates, TO
中科院分区：
文献类型：
--
作者：
Padilla, JE;Yeates, TO
提出了一种分析大分子单晶 X 射线衍射强度统计的新方法。不考虑分辨率壳中的反射，而是分别获取局部反射强度对之间的差异并进行归一化。当适当选择要比较的两个反射（分别具有强度 I-1 和 I-2）时，参数 L = (I-1 - I-2)1(I-1 + I-2) 的行为对容易混淆传统强度统计的现象不敏感，例如各向异性衍射和伪中心。当强度数据来自普通晶体或完美孪生样本时，L 的分布和期望值采用简单的形式。该方法的稳健性通过使用真实蛋白质的示例来证明，其衍射数据通过其他强度分析方法显得异常。新的统计数据比其他可用的方法更适合诊断完美半面体孪晶。
A new approach to analyzing macromolecular single-crystal X-ray diffraction intensity statistics is presented. Instead of considering reflections in resolution shells, differences between local pairs of reflection intensities are taken and normalized separately. When the two reflections to be compared (having intensities I-1 and I-2, respectively) are chosen appropriately, the behavior of the parameter L = (I-1 - I-2)1(I-1 + I-2) is insensitive to phenomena that tend to confound traditional intensity statistics, such as anisotropic diffraction and pseudo-centering. The distributions and expected values for L take simple forms when the intensity data are from ordinary crystals or from perfectly twinned specimens. The robustness of the approach is demonstrated with examples using real proteins whose diffraction data appear aberrant by other methods of intensity analysis. The new statistic is better suited than other available methods for diagnosing perfect hemihedral twinning.