Temperature dependence of rotational disorder in a non-standard amino acid from X-ray crystallography and molecular dynamics simulation.
Temperature dependence of rotational disorder in a non-standard amino acid from X-ray crystallography and molecular dynamics simulation.
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X 射线晶体学和分子动力学模拟中非标准氨基酸旋转无序的温度依赖性。
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
B. Corry
中科院分区：
文献类型：
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作者：
B. Dittrich;J. Warren;F. Fabbiani;W. Morgenroth;B. Corry
报道了非标准氨基酸2-氨基异丁酸甲酯盐酸盐(Me-AIB)在10、30、50、70和100K下的X-射线单晶结构，傅立叶谱表明甲酯基氢原子存在旋转无序。为了详细研究这种影响，用同步辐射收集了高分辨率的数据。用不变散射因子预测了非球形分子的电子密度，并从完全多极修正得到的密度中减去了非球形电子密度。这使得无序可以从每个温度下的分子电子密度中区分出来。无序度在100K到30K之间降低，但即使在10K下仍可检测到。因此，可以应用不同的密度来验证电子结构，并且与傅立叶方法相比具有无噪声的优点。超低温实验预计将有助于减少超高分辨率蛋白质结晶学中的这种无序。在10-100K温度下对Me-AIB进行的分子动力学模拟证实了实验观察到的甲基旋转运动的温度依赖性。X射线结构分析中的无序建模将是分子动力学模拟的一个有趣的未来应用。
The X-ray single-crystal structure of methyl 2-aminoisobutyrate hydrochloride (Me-AIB), a non-standard amino acid, is reported at 10, 30, 50, 70 and 100 K. Fourier maps indicate the presence of rotational disorder of the hydrogen atoms of the ester methyl group. To study this effect in detail, high resolution data were collected with synchrotron radiation. The non-spherical molecular electron density was predicted with invariom scattering factors and subtracted from the density obtained from a full multipole refinement. This allows disorder to be distinguished from the molecular electron density at each temperature. The disorder is reduced between 100 K and 30 K, but still detectable even at 10 K. Hence, difference densities can be applied for the purpose of electronic structure validation and have the advantage of an absence of noise over Fourier methods. Ultra-low temperature experiments are foreseen to be useful in reducing such kinds of disorder in ultra-high resolution protein crystallography. Molecular dynamics simulations of Me-AIB at temperatures between 10 and 100 K confirm the temperature dependence of the rotational motion of the methyl group seen experimentally. Modeling disorder in X-ray structure analysis will be an interesting future application of molecular dynamics simulations.
DOI：
10.1107/s0108767302010991
发表时间：
2002
期刊：
Acta crystallographica. Section A, Foundations of crystallography
影响因子：
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作者：
Koritsanszky,Tibor;Volkov,Anatoliy;Coppens,Philip
通讯作者：
Coppens,Philip