Reducing dynamical electron scattering reveals hydrogen atoms
Reducing dynamical electron scattering reveals hydrogen atoms
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DOI：
10.1107/s2053273318013918
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发表时间：
2019-01-01
影响因子：
1.8
通讯作者：
Abrahams, Jan Pieter
中科院分区：
文献类型：
--
作者：
Clabbers, Max T. B.;Gruene, Tim;Abrahams, Jan Pieter
与x射线相比，电子衍射面临着一个关键的挑战：动态电子散射损害了结构解，其影响只能在特定情况下建模。动态散射可以通过减小晶体尺寸来减少，但不是没有惩罚，因为它也降低了总体衍射强度。在这篇文章中，它表明，纳米大小的晶体从有机药物允许氢原子的位置细化，即使忽略了在细化过程中的动态散射的影响。为了增强微弱的衍射数据，采用了高灵敏度的混合像元探测器。为了进一步减少动态散射的不利影响，本文还引入了一种基于一般似然的计算方法，这大大提高了模型的精度，即使对于分辨率低得多的蛋白质晶体数据也是如此。
Compared with X-rays, electron diffraction faces a crucial challenge: dynamical electron scattering compromises structure solution and its effects can only be modelled in specific cases. Dynamical scattering can be reduced experimentally by decreasing crystal size but not without a penalty, as it also reduces the overall diffracted intensity. In this article it is shown that nanometre-sized crystals from organic pharmaceuticals allow positional refinement of the hydrogen atoms, even whilst ignoring the effects of dynamical scattering during refinement. To boost the very weak diffraction data, a highly sensitive hybrid pixel detector was employed. A general likelihood-based computational approach was also introduced for further reducing the adverse effects of dynamic scattering, which significantly improved model accuracy, even for protein crystal data at substantially lower resolution.