NEW FLOW CELLS FOR HIGHER-THROUGHPUT SOLUTION SCATTERING STUDIES

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。 我们最近开发了两种类型的流动池来提高生物大分子的溶液X射线散射研究中的数据收集效率。这两个池都结合了标称直径为1.5 mm的薄壁石英或硼硅酸盐玻璃毛细管，以在X射线束中容纳低至~5微升的样品等分。第一种类型的毛细管位于一个短圆柱形铝件的中心，两端都有一个NW25真空接头。它直接连接到紧靠样品台下游的窗口凸缘，另一端通过下面的短柔性连接到紧靠样品台上游的保护狭缝。它通过将上游和下游真空路径连接在一起，完全消除了气隙，达到了研究小蛋白质和多肽所需的绝对最低本底水平。第二种流动池是对第一种流动池的补充，使毛细管位于真空路径外，以便更快地对准，允许用户在遇到严重辐射损害时在非常短的时间内从标准聚碳酸酯池切换，而在大多数情况下，可以通过在光束中轻轻流动样品等份来有效地消除辐射损害。这种电池只需要7毫米的气隙，而且对于大多数溶液散射研究来说，背景水平仍然相当低。这种设计也比真空版本的故障排除更容易。任一电池都通过细长的Tygon管连接到汉密尔顿540B样品分配器，用于样品装载和由BLU-ICE远程控制的流动。在这两种情况下，样品温度控制都是通过使用标准冷藏Neslab水浴使水流过电池主体来完成的。

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. We have recently developed two types of flow cells to improve data collection efficiency in solution x-ray scattering studies of biological macromolecules. Both cells incorporate a thin-wall quartz or borosilicate glass capillary of 1.5 mm nominal diameter to hold a sample aliquot as little as ~5 microliter in the x-ray beam. The first type has the capillary positioned at the center of a short cylindrical aluminum piece which has a NW25 vacuum fitting on both ends. It is directly connected to the window flange immediately downstream of the sample stage and the other end is connected to the guard slit, immediately upstream of the sample stage, via a short flexible below. It has achieved an absolutely minimum background level, which is required for studying small proteins and peptides, by eliminating the air gap completely by connecting together the upstream and downstream vacuum paths. The second flow cell complements the first one by having the capillary outside of the vacuum path for much quicker alignment, allowing users to switch from the standard polycarbonate cells within a very short time upon encountering severe radiation damage which can be effectively eliminated in most cases by flowing the sample aliquot gently in the beam. A mere 7 mm air gap is required for this cell, and the background level is still reasonably low for most solution scattering studies. This design also allows easier troubleshooting than for the in-vacuum version. Either cell is connected to a Hamilton 540B sample dispenser via thin Tygon tubing for sample loading and flow remotely controlled by Blu-ICE. In both cases, sample temperature control is accomplished via flowing water through the cell body using a standard refrigerated Neslab water bath.