Bartunik H D, Borchert T
Max-Planck Society, Research Unit for Structural Molecular Biology, Hamburg, Federal Republic of Germany.
Acta Crystallogr A. 1989 Oct 1;45 ( Pt 10):718-26. doi: 10.1107/s0108767389006604.
A novel strategy of macromolecular structure analysis is described which combines the use of monochromatic scanning Laue (SCL) and white-beam Laue (WBL) diffraction techniques. It provides, when applied with an area detector with on-line capabilities, a means of interactively determining and optimizing experimental parameters; it further makes rapid data evaluation feasible, also with off-line detector systems. These new procedures have been applied to a protein structure, beta-trypsin, using a FAST area detector (Enraf-Nonius) and image plates (Fuji) on a double-focusing synchrotron beamline at DORIS. Structure factors, which were derived from FAST Laue data, were empirically scaled by comparing equivalent reflections in different wavelength bins. A 2Fo-Fc difference Fourier map, which was calculated at 1.8 A resolution using these structure-factor moduli together with phases from the known structural model, showed well defined electron density distribution (R = 22%). Image-plate exposures showed diffraction to 1.2 A resolution. The effect of crystal mosaicity on the maximum wavelength bandwidth for Laue exposures has been investigated. SCL techniques, which involve rapid scanning (with a crystal or multilayer monochromator or a tunable undulator) through a defined wavelength range, extend the applicability of Laue techniques to crystals with broadened mosaic spread.
本文描述了一种大分子结构分析的新策略，该策略结合了单色扫描劳厄（SCL）和白光劳厄（WBL）衍射技术的使用。当与具有在线功能的面积探测器一起应用时，它提供了一种交互式确定和优化实验参数的方法；它还使快速数据评估变得可行，即使使用离线探测器系统也是如此。这些新程序已应用于一种蛋白质结构——β-胰蛋白酶，使用了FAST面积探测器（恩拉夫-诺尼乌斯公司）和成像板（富士公司），在多丽丝的双聚焦同步加速器光束线上进行实验。通过比较不同波长区间内的等效反射，对从FAST劳厄数据中导出的结构因子进行了经验性缩放。使用这些结构因子模量以及来自已知结构模型的相位，在1.8埃分辨率下计算得到的2Fo - Fc差值傅里叶图显示出定义良好的电子密度分布（R = 22%）。成像板曝光显示衍射分辨率达到1.2埃。研究了晶体镶嵌性对劳厄曝光最大波长带宽的影响。SCL技术涉及通过定义的波长范围进行快速扫描（使用晶体或多层单色仪或可调谐波荡器），将劳厄技术的适用性扩展到具有加宽镶嵌展宽的晶体。
