NEW FLOW CELLS FOR HIGHER-THROUGHPUT SOLUTION SCATTERING STUDIES

该子项目是利用 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来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 我们最近开发了两种类型的流动池，以提高数据收集效率的生物大分子的溶液X射线散射研究。两种样品池均包含标称直径为1.5 mm的薄壁石英或硼硅酸盐玻璃毛细管，可在X射线束中容纳约5微升的样品等分试样。 第一种类型的毛细管位于短圆柱形铝件的中心，该铝件在两端具有NW 25真空接头。它直接连接到样品台下游的窗口法兰，另一端通过下面的短柔性连接到样品台上游的防护狭缝。通过将上游和下游真空路径连接在一起，完全消除了气隙，实现了研究小蛋白质和肽所需的绝对最低背景水平。第二个流动池与第一个流动池互为补充，因为毛细管位于真空通道之外，可以更快地对齐，允许用户在遇到严重辐射损伤时在很短的时间内从标准聚碳酸酯池切换，在大多数情况下，通过使样品等分试样在光束中轻轻流动，可以有效地消除辐射损伤。该电池仅需7 mm的气隙，对于大多数溶液散射研究，背景水平仍然相当低。这种设计也允许比真空版本更容易的故障排除。每一个池都通过薄Tygon管连接到汉密尔顿540 B样品分配器，用于由Blu-ICE远程控制的样品加载和流动。在这两种情况下，样品温度控制是通过使用标准冷藏Neslab水浴使水流过池体来实现的。

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. 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.