AUTOMATIC CENTERING OF PROTEIN CRYSTALS USING X-RAYS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 为了完全自动化晶体筛选过程，改进了将蛋白质晶体与X射线束自动对准的方法。这些方法侧重于使用在X射线束中不同晶体位置拍摄的低剂量衍射图像的平均I/Sig(I)。使用图像分析程序DISTL对这些图像进行分析，以估计I/Sig(I)，并在此分析的基础上，在特定算法中检查和改进一系列参数，以实现最佳晶体排列，确定并使用晶体而不是光学中心的最大衍射力。在资助年度内，在每条大分子结晶学光束线上粗略地测试了样品居中的算法。这些测试表明，不同的光束特性需要进一步改进算法，这是通过开发光束与测角仪的Phi轴自动对准来实现的。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In order to fully automate the crystal screening process, methods to automatically align protein crystals to the x-ray beam were refined. The approaches focus on using average I/Sig(I) from low-dose diffraction images taken at various crystal positions in the x-ray beam. These images are analyzed using the image analysis program, DISTL, in order to estimate I/Sig(I), and based on this analysis, a range of parameters are examined and refined in specific algorithms for optimal crystal alignment, determining and using the maximum diffracting power of the crystal rather than the optical center. During the grant year, the algorithm for centering samples was thouroughly tested on each macromolecular crystallography beam line. These tests revealed that different beam characteristics necessitated further refinement of the algorithms, which was accomplished through the development of auto-alignment of the beam to the phi axis of the goniometer.