RADIATION DAMAGE AS A FUNCTION OF WAVELENGTH

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。辐射损伤是异常色散相移实验的一个严重问题，因为在MAD或SAD实验中，样品在感兴趣的典型波长处的吸收增加。结果表明，在纽卡林的情况下，在吸收边拐点的数据采集和10度楔形的远距离波长允许结构解，而常规的三波长MAD实验和最大能量下的SAD是无效的。进行实验以确定a)上述结果是否适用于其他蛋白质，以及b)在这种情况下促进结构解决的关键因素是什么：在楔形中同时收集所有波长的数据，或避免在最大f‘’波长收集数据。本实验对来自根癌农杆菌的假想蛋白质(NP_356412.1)和来自鼠伤寒沙门氏菌的推测的氨基葡萄糖-果糖-6-磷酸转氨酶(16423107)的晶体进行了实验：从几个晶体中收集了连续的MAD和SAD实验，直到观察到实质性的衍射损伤(在高分辨率下衍射点大幅减少)。随着晶体吸收总剂量的增加，晶相的质量逐渐下降。在双波长MAD实验的情况下，只要数据是以楔形数据收集的，在实质性辐射损伤后，电子密度图仍然可以被解释。然而，当两个波长连续收集时，结构溶液在较低的总吸收剂量下失败

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. Radiation damage is a serious concern for Anomalous Dispersion phasing experiments because of the increased absorption by the sample at the typical wavelength of interest for MAD or SAD experiments. It has been found that data collection at the absorption edge inflection point and the remote wavelength in 10 degrees wedges allowed structure solution in the case of vinculin, where conventional three-wavelength MAD experiments and SAD at the maximum f¿¿ energy failed. Experiments were carried out to determine a) if the above results are valid for other proteins and b) what is the critical factor which facilitates structure solution in such cases: simultaneous data collection at all wavelengths in wedges, or avoiding data collection at the maximum f'' wavelength. The experiments were carried out on crystals of the hypothetical protein (NP_356412.1) from Agrobacterium tumefaciens and a putative glucosamine-fructose-6-phosphate aminotransferase (16423107) from Salmonella typhimurium: Successive MAD and SAD experiments were collected from several crystals until substantial diffraction damage (substantial decrease of diffraction spots at high resolution was observed. The quality of the phases decreased steadily as the total dose absorbed by the crystals increased. In the case of two-wavelength MAD experiments the electron density maps could still be interpreted after substantial radiation damage as long as the data were collected in wedges. However, when the two wavelengths were collected consecutively, structure solution failed at a lower total absorbed do