DEVELOPMENTS FOR SINGLE CRYSTAL XAS INSTRUMENTATION

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 单晶X射线吸收光谱允许连续测量X射线衍射和X射线吸收数据，使实验者能够同时获得蛋白质或小分子活性位点的全局结构和原子级局部结构信息。在2009年期间，对单晶XAS设置进行了增量更改。 机械重排使得Mar 345图像板检测器（其大于原始Mar 165 CCD）能够更优化地定位，以改善相对于光束的居中，并且因此在确定晶体取向矩阵和晶胞参数时具有更高的精度。在特别容易与分子氧结合和反应的蛋白质样品上测试了液态He冷冻流的灵敏度。这些测试将扩展到已经用X射线照射的样品，以研究可能的分子光激发和氧化还原电位变化的氧化速率变化。

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. Single crystal x-ray absorption spectroscopy allows for the sequential measurement of x-ray diffraction and x-ray absorption data enabling the experimenter to obtain simultaneous global structure and atomic-level local structure information of a protein or small molecule active site. Incremental changes were made to the single crystal XAS setup during 2009. A mechanical rearrangement enabled the Mar345 image plate detector (which is larger than the original Mar165 CCD) to be more optimally positioned for improved centering with respect to the beam and accordingly a higher accuracy in the determination of crystal orientation matrices and cell parameters. The sensitivity of the liq He cryostream was tested on protein samples that are especially susceptible to binding and reactivity with dioxygen. These tests will be extended to samples that have been irradiated with x-rays to investigate changed rates of oxygenation with possible photo-excitation of the molecule and changes in redox potentials.