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

我们申请为我们现有的低温电子显微镜设备升级最先进的直接电子检测器/能量过滤器。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。使用新型的直接电子探测器，单粒子分析通常达到3 μ m及以下的分辨率，使cryo-EM成为结构生物学中广泛问题的首选方法。检测器/能量过滤器技术的最新发展与先进的图像处理软件相结合，实现了又一次定量和定性的飞跃，现在可以更快地收集数据，对成分和构象异质性进行更详尽的分类，分辨率极限可低至1.2-1.5 μ m。为了收集足够量的数据以达到有助于例如基于结构的药物设计的分辨率，以我们目前的设备和能力，需要非常多的收集时间，并且几乎不可能达到低于2 μ m的分辨率。尽管我们所有的低温EM仪器基本上每周7天/24小时使用，停机时间很少，但其容量无法满足不断增长的需求以及全球范围内对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），曝光时间比其前身短数倍。因此，我们申请购买高端直接电子探测器和能量过滤系统，预计将增加可用的数据收集时间，更重要的是，还可以提高质量。更具体地说，拟议的探测器/滤波器系统计划安装在我们较新的300 keV仪器上，而现有的探测器/滤波器系统将重新安置到较旧的仪器上。因此，新装置的数据收集能力和质量将允许对小颗粒、具有罕见构象或组成状态的复合物和大分子复合物进行分析，其分辨率足够高，可用于所有计划的应用。

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.