LIQUID-LIKE MOVEMENTS IN CRYSTALLINE INSULIN
LIQUID-LIKE MOVEMENTS IN CRYSTALLINE INSULIN
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DOI：
10.1038/332659a0
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发表时间：
1988-04-14
期刊：
影响因子：
64.8
通讯作者：
CLARAGE, M
中科院分区：
文献类型：
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作者：
CASPAR, DLD;CLARAGE, J;CLARAGE, M
蛋白质晶体的漫X射线散射提供了有关分子灵活性和包装不规则性的信息1 -4。在这里，我们分析胰岛素晶体的衍射图案，显示两种类型的散射有关的障碍：非常弥漫，液体状衍射，和周围的布拉格反射晕。晕是由于晶格中相邻分子的耦合位移，而非常漫散射是由于原子位置的变化导致的，这些变化仅在每个分子内局部相关。测量的强度被数字化地分成三个分量：布拉格反射和相关的晕;水和康普顿散射;以及归因于内部蛋白质运动的散射。我们扩展了用于分析膜结构中的无序的方法5 - 7，以模拟结晶胰岛素的漫散射，包括（1）理想有序晶体结构的Patterson（自相关）函数，（2）均方根（r.m.s.）原子运动的幅度，以及（3）这些位移耦合的平均距离。分子内原子的运动，具有r.m.s. 0.4-0.45 Ω的振幅，似乎在~6 Ω的范围内耦合，如在液体中。这些局部耦合运动解释了晶体中的大部分无序。而且，蛋白质分子作为一个整体，在晶格中以均方根值摆动。振幅约为0.25 kHz，似乎仅在最近的邻居之间显著相关。
Diffuse X-ray scattering from protein crystals provides information about molecular flexibility and packing irregularities1–4. Here we analyse diffraction patterns from insulin crystals that show two types of scattering related to disorder: very diffuse, liquid-like diffraction, and haloes around the Bragg reflections. The haloes are due to coupled displacements of neighbouring molecules in the lattice, and the very diffuse scattering results from variations in atomic positions that are only locally correlated within each molecule. The measured intensity was digitally separated into three components: the Bragg reflections and associated haloes; the water and Compton scattering; and the scattering attributed to internal protein movements. We extend methods used to analyse disorder in membrane structures5–7to simulate the diffuse scattering from crystalline insulin in terms of (1) the Patterson (autocorrelation) function of the ideal, ordered crystal structure, (2) the root-mean-square (r.m.s.) amplitude of the atomic movements, and (3) the mean distance over which these displacements are coupled. Move-ments of the atoms within the molecules, with r.m.s. amplitudes of 0.4–0.45 Å, appear to be coupled over a range of ~6 Å, as in a liquid. These locally coupled movements account for most of the disorder in the crystal. Also, the protein molecules, as a whole, jiggle in the lattice with r.m.s. amplitudes of ~0.25 Å that appear to be significantly correlated only between nearest neighbours.