Acquition of a microdiffractometer for SER-CAT

描述（由申请人提供）：在分子生物学、同步加速器X射线、晶体冷却、检测器、定相方法和结构基因组学（特别是与结构测定过程的所有方面相关的高通量方法）技术进步的帮助下，蛋白质结构测定出现了爆炸性增长。据估计，所有新结构的80%是使用同步加速器X射线确定的，许多设施正在升级其光束线设施，以满足这一需求，并提供新的功能，如从微晶（尺寸小于50？的晶体）收集数据。对微衍射能力的需求反映了随着社区将其研究扩展到更大和更困难的系统，需要收集越来越小的晶体数据。例如，膜蛋白既难以生产又难以结晶，因此获得用于衍射研究的大晶体是非常困难的。同样，在另一个领域，蛋白质-蛋白质杂合复合物的研究、完整复合物的生产和结晶是困难的，并且难以获得复合物的大晶体。在这两种情况下，许多正在研究的系统都是潜在的治疗靶点。该提案直接反映了东南区域合作访问小组（SER-CAT）成员的愿望-来自26个机构（学术，工业，私人和政府）的90多个研究小组-在高级光子源的波荡器光束线（22 ID）上的微衍射能力，正如SER-CAT执行委员会2007年3月17日会议期间讨论的那样。由于这些团体中的大多数（约75个资助的研究项目）正在进行NIH资助的校外研究，对NIH研究计划的影响应该是显着的。为了满足在数据收集期间保持微束中的微晶的需求，必须解决三个方面：束尺寸和形状、晶体成像和测角。所提出的MAATEL MD 2微衍射仪满足了这些需求。光束大小-100？22 ID X射线束太大。它可以减少使用针孔类似，但SER-CAT缺乏用户友好的光束成像和诊断工具的MD 2;晶体成像-SER-CAT晶体成像系统不能很容易地成像微晶，使对齐和数据收集在分50？晶体很难，如果不是不可能的话。MD 2的轴上显微镜与轴上照明相结合，使发现和排列微晶变得更加容易。此外，对X射线束的大小、形状和位置（来自光束成像）的精确了解确保了微晶位于微束的中心; SER-CAT使用的Rosenbaum测角仪的混淆球太大，无法确保在数据收集期间晶体旋转时微晶保留在微束中。MD 2测角仪有一个2米的混淆球和一个空气轴承测角仪。这种组合确保了10？晶体在数据收集期间保持在光束中。SER-CAT认为MD 2是为其成员提供微衍射功能的最具成本效益的解决方案。如果获得资助，将提高微衍射实验和一般衍射实验（包括远程数据收集）的光束线操作的生产率和成本效益。这反过来又会产生更多更好的科学。公共卫生相关性：蛋白质的三维结构的知识可以在理解基本的生物过程和治疗剂的设计中是一个很大的帮助。然而，为了了解蛋白质-配体（药物）或蛋白质-蛋白质相互作用的详细性质，需要通常使用同步加速器X射线收集的高分辨率X射线衍射数据。随着社区将其研究扩展到更大和更困难的系统，蛋白质生产和结晶都变得有问题，通常导致即使使用同步加速器X射线也太小而无法收集数据的微晶。申请资金用于购买MAATEL MD 2微衍射仪，该仪器将允许对这些微晶进行数据收集，并将对基于同步加速器的X射线结构生物学的生产率和成本效益产生重大影响，从而产生更多更好的科学。

DESCRIPTION (provided by applicant): Aided by technological advances in molecular biology, synchrotron X-rays, crystal cooling, detectors, phasing methods and structural genomics (notably high-throughput methods related to all aspects of the structure determination process) there has been an explosive growth in protein structure determination. It is estimated that fully 80% of all new structures are determined using synchrotron X-rays and many facilities are upgrading their beamlines facilities to meet this demand and to offer new capabilities, such as data collection from micro crystals (crystals whose dimensions are less than 50 ?). The desire for microdiffraction capability reflects need to collect data on smaller and smaller crystals as the community expands its research into larger and more difficult systems. For example, membrane proteins are both difficult to produce and crystallize, thus obtaining large crystals for diffraction studies is very difficult. Again, in another area, the study of protein- protein hetero complexes, production and crystallization of the intact complex is difficult and large crystals of the complex are hard to obtain. In both cases many of the systems under study are potential therapeutic targets. This proposal is a direct reflection of the desire of the Southeast Regional Collaborative Access Team's (SER-CAT) membership -- 90 plus research groups from 26 institutions (academic, industry, private and government) -- for microdiffraction capabilities on its undulator beamline (22ID) at the Advanced Photon Source, as was discussed during the March 17, 2007 meeting of the SER-CAT Executive Board. Since a majority of these groups (~75 funded research projects) are carrying out NIH funded extramural research the impact to NIH research program should be significant. To meet the demands of maintaining a microcrystal in a microbeam during data collection, three areas must be addressed beam size and shape, crystal imaging and goniometry. The proposed MAATEL MD2 microdiffractometer addresses these needs. Beam size - the 100? 22ID X-ray beam is too large. It can be reduced using pinholes similar but SER-CAT lacks the user-friendly beam imaging and diagnostic tools of the MD2; Crystal imaging - the SER-CAT crystal imaging system cannot easily image microcrystals, making alignment and data collection on sub 50? crystals difficult if not impossible. The on-axis microscope of the MD2 coupled with on-axis illumination makes it much easier to find and align microcrystals. In addition, the precise knowledge of the X-ray beam's size, shape and location (derived from beam imaging) insures that the microcrystal is centered in the microbeam; Goniometey - the ~5-10? sphere of confusion of the Rosenbaum goniometer used at SER-CAT is too large to ensure that microcrystal remains in the microbeam as the crystal is rotated during data collection. The MD2 goniometer has a 2msphere of confusion and an air bearing goniometer. This combination ensures that a 10??crystal remains in the beam during data collection. SER-CAT believes that the MD2 represents the most cost-effective solution for providing microdiffraction capabilities to its members. If funded will result in increased productivity and cost-effectiveness of beamline operation for both micro and general diffraction experiments (including remote data collection). This in turn will more and better science being produced. PUBLIC HEALTH RELEVANCE: Knowledge of a protein's 3-Dimensional structure can be a great aid in understanding fundamental biological processes and in the design of therapeutic agents. However, to understand the detailed nature of protein-ligand (drug) or protein-protein interactions high-resolution X-ray diffraction data, usually collected using synchrotron X-rays is required. As the community expands its research into larger and more difficult systems both protein production and crystallization become problematic usually resulting in microcrystals that are too small for data collection even when using synchrotron X-rays. Funds are requested to purchase a MAATEL MD2 microdiffractometer that will allow data collection on these microcrystals and should significantly impact the productivity and cost- effectiveness of synchrotron based X-ray structural biology resulting in more and better science being produced.