Electron detector and energy filter for an high-resolution cryo-electron microscope

我们申请最先进的直接电子探测器/能量过滤器升级我们现有的冷冻电子显微镜设备。低温电子显微镜（cryo-EM）的最新技术发展在提高分辨率和适用性方面取得了巨大的科学进步。使用新型直接电子探测器，单粒子分析通常达到或低于3 Å的分辨率，使冷冻电镜成为结构生物学中广泛问题的选择方法。探测器/能量滤波技术的最新发展与先进的图像处理软件相结合，达到了又一次定量和定性飞跃的高潮，现在允许更快的数据收集，更详尽的成分和构象异质性分类和分辨率限制达到1.2-1.5 Å。为了收集足够数量的数据以达到分辨率，例如促进基于结构的药物设计，以我们目前的设备和能力，需要大量的收集时间，分辨率低于2 Å几乎是不可能的。虽然我们所有的低温电镜仪器基本上每周7天24小时使用，很少停机，但其容量无法满足不断增长的需求和全球范围内数据数量和质量的变化。最新一代的直接电子探测器具有更高的探测量子效率（DQE），曝光时间比其前身缩短了几倍。因此，我们申请购买一个高端的直接电子探测器和能量过滤系统，这有望增加可用的数据收集时间，更重要的是，也提高了质量。更具体地说，拟议的探测器/过滤系统计划安装在我们新的300keV仪器上，而现有的探测器/过滤系统将被重新安置在旧仪器上。因此，新装置的数据收集能力和质量将允许以足够高的分辨率分析小颗粒，具有罕见构象或组成状态的复合物以及所有计划应用的大分子复合物。

We apply for a state-of-the-art direct electron detector/energy filter upgrade for our existing cryo-electron microscopy facility. The recent technological developments in cryo-electron microscopy (cryo-EM) have led to a great scientific progress with respect to improved resolution and, hence, in its applicability. Using the novel direct electron detectors, single particle analysis has routinely reached resolutions at and below 3 Å, making cryo-EM the method of choice for a broad range of questions in structural biology. Newest developments in detector/energy filter technology in combination with advanced image processing software has culminated in yet another quantitative and qualitative leap, now allowing much faster data collection, more exhaustive classification of compositional and conformational heterogeneity and a resolution limit reaching down to 1.2-1.5 Å. In order to collect sufficient amount of data to reach a resolution facilitating e.g. structure-based drug design, with our current equipment and capacity an extraordinary amount of collection time would be necessary and resolutions below 2 Å are barely possible. Although all of our cryo-EM instruments are utilized essentially 24 hours/7 days a week with very little down-time, the capacity cannot satisfy the increasing demand and worldwide shifting state of the art for data quantity and quality. The latest generation of direct electron detectors have an improved detective quantum efficiency (DQE) and exposure times are several times shorter than with its predecessor. Therefore, we apply to purchase a high-end direct electron detector and energy filter system, which is expected to increase available data collection time and, importantly, also quality. More specifically, the proposed detector/filter system is planned to be installed at our newer 300keV instrument, whereas the existing detector/filter system will be relocated to the older instrument. As a result, the data collection capacity and quality of the new setup will allow analysis of small particles, of complexes with rare conformational or compositional states and of macromolecular complexes at sufficiently high resolution for all planned applications.