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首页> 外文学位 >High-resolution x-ray diffraction investigation of radiation damage in hen egg white lysozyme crystals.
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High-resolution x-ray diffraction investigation of radiation damage in hen egg white lysozyme crystals.

机译：鸡蛋蛋白溶菌酶晶体中辐射损伤的高分辨率x射线衍射研究。

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High-resolution X-ray diffraction was used to examine small changes in diffracted intensity from hen egg white lysozyme crystals due to radiation damage with the goal of showing the usefulness of this technique to detect defects in protein crystals. A rotating anode generator with four-circle diffractometer was equipped with two graded, parabolic mirrors to permit these measurements in a modest, laboratory environment. An metric, two-reflection silicon monochromator showed the best compromise between reducing wavelength dispersion and decreasing flux. Triple axis reciprocal space maps of reflections from different lysozyme crystals and different X-ray reflections within the same crystal show significant, measurable differences, which means that this technique can indeed be used in the protein crystallography community. A discussion of whether protein crystals diffract kinematically or dynamically is given. As a first investigation, changes in diffracted intensity near a Bragg peak from two lysozyme crystals were monitored during an X-ray irradiation study. Interestingly, the widths of the peaks originally decreased, implying a brief increase in structural quality. At long irradiation times, the peak intensity decreased as the peak widths increased, which would be expected for a system with increasing disorder and defects. Most of the diversion of diffracted intensity appeared as an anisotropic mosaic spread. If the transition between Huang and Stokes-Wilson regimes represents a characteristic size (i.e., a defect size) causing the scattering mechanism to change as it does for semiconductor materials, then this characteristic size is shown to be on the order of microns, and to decrease over the irradiation study. Possible mechanisms for radiation-induced protein crystal defects are discussed.
机译：高分辨率X射线衍射用于检查由于辐射损伤而引起的鸡蛋清溶菌酶晶体衍射强度的微小变化，目的是证明该技术可用于检测蛋白质晶体中的缺陷。具有四圆衍射仪的旋转阳极发生器配有两个渐变的抛物面镜，以允许在适度的实验室环境中进行这些测量。公制，两反射硅单色仪显示出在减少波长色散和减少通量之间的最佳折衷方案。来自不同溶菌酶晶体的反射和同一晶体内不同X射线反射的三轴倒数空间图显示出明显的，可测量的差异，这意味着该技术确实可以用于蛋白质晶体学领域。讨论了蛋白质晶体是运动学衍射还是动态衍射。作为首次研究，在X射线辐照研究期间，监测了两个溶菌酶晶体在布拉格峰附近的衍射强度变化。有趣的是，峰的宽度最初减小了，这意味着结构质量得到了短暂的提高。在较长的辐照时间下，峰强度会随着峰宽的增加而降低，这对于无序和缺陷增加的系统是可以预期的。衍射强度的大部分转移表现为各向异性的马赛克扩散。如果在Huang和Stokes-Wilson态之间的过渡表示特征尺寸（即缺陷尺寸），导致散射机制像半导体材料一样发生变化，则表明该特征尺寸约为微米级，并且减少辐射研究。讨论了辐射诱导的蛋白质晶体缺陷的可能机制。

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