Development of Protein Crystallography System at Ultralow Temperature

我们开发了一个完整的系统，该系统可以在从室温到液氮温度的任意温度下以高分辨率和高速进行蛋白质晶体学的x射线衍射数据收集。该系统可以实现1)在x射线衍射仪上高速、高精度的数据采集，2)在超低温下的x射线强度数据采集，3)通过计算机工作站控制的整个系统进行实时晶体学计算，进行结构分析。介绍了一种双弯镜单色系统在二维区域检测器中的应用。开发了用于单色仪的附件，以实现光束线的对准。为了在低温下收集强度数据，我们对蛋白质晶体采用了直接冷冻法。以溶菌酶为例，该方法可以在低温下收集数据，但晶体的嵌合性增加。为了使晶体保持低温，我们使用了液氮气体流动装置。结果表明，该系统可用于上述冷冻晶体的数据采集。建立了总站网络系统，对衍射仪进行控制和晶体学计算。

We have developed a total system in which X-ray diffraction data collection for protein crystallography can be performed with high resolution and high speed at an arbitrary temperature from room to liquid nitrogen temperatures. This system can perform 1) high-speed and high accuracy data collection on the X-ray diffractometer having the two-dimensional area detector equipped with an imaging plate, 2) X-ray intensity data collection at ultralow temperature and 3) real-time crystallographic calculations for structure analysis by the total system controlled by the computer workstation.We introduced a double-bent mirror monochromator system in the two-dimensional area detector. The attachments for the monochromator were developed to achieve the alignment of the beam line. In order to collect intensity data at low temperature we employed a direct freezing method for protein crystals. In case of lysozyme, it was possible to collect the data at low temperature by this method, although the mosaicity of crystals increased. To keep the crystal at low temperature, we employed a gas-flow apparatus using liquid nitrogen. It was found that this system can use for the data collection of the forzen crystals above mentioned.The total workstation network system was established to control the diffractometer and perform crystallographic calculations.