High Efficiency Linked Scan Mass Spectrometer

翻译后修饰与细胞内蛋白质功能的调节密切相关。 检测蛋白质修饰的存在并量化它们的丰度是 了解它们在生物过程中的作用。尽管在使用几种技术方面取得了一定的成功，如 随着放射学、埃德曼测序和免疫化学揭示修饰，这项研究继续 提出了艰巨的分析挑战。基于质谱学的方法开始发挥作用 在这项任务中发挥着越来越重要的作用。几种类型肿块的联动扫描操作模式 光谱仪在检测和分析几种类型的修饰方面表现出了非凡的前景。这个 技术是高度选择性的，基于观察到特定特征片段的重合度 在化合物的碎裂光谱中。目前，这种模式的效率只达到了很小的一部分 由于前驱体离子选择步骤，在该步骤期间所有其他离子被拒绝链接扫描 分析。本项目的目标是(1)建立一种新型的用于收集链接扫描的质谱计 效率接近100%的光谱和(2)实现该质谱仪用于检测和剖析 蛋白质上的修饰位点。质谱计的结构是基于一种新的高离子 串联配置的四极碰撞池和四极组合的电容线离子陷阱 质量分析器。这种新型的线性离子陷阱可以在不降解的情况下存储大量的离子 由于空间电荷的影响而产生的性能。存储在离子捕获器中的所有离子都可以被顺序碎片化 但只有特定的离子碎片才能被传输到 通过四极质量分析器，其扫描与离子陷阱喷射扫描相关联。因此，一个 在单次扫描期间，可以从存储在离子陷阱中的所有离子获得链接扫描光谱 使仪器的效率提高100-1000倍。这台质谱仪可以 用于检测蛋白质的修饰位点，具有前所未有的速度和灵敏度。它将有一个 对于监测复杂混合物中的特定产品，并最终收集 所有观察到的物种的碎片光谱。一旦建成，它将很快成为不可或缺的 推动生物医学研究前沿的研究工具。

Post-translational modifications are intimately involved in regulation of the protein function in the cell. Detecting the presence of modifications on proteins and quantifying their abundance is a prerequisite for understanding their role in biological processes. Despite a certain success in using several techniques such as radiography, Edman sequencing and immunochemistry to reveal modifications, this study continues to present formidable analytical challenge. Mass spectrometry based methods are beginning to play an increasingly important role in this task. A linked scan mode of operation of several types of mass spectrometers exhibits an exceptional promise for detecting and profiling several types of modifications. The technique is highly selective and based on the coincidence of observing a particular characteristic fragment in the fragmentation spectrum of a compound. Presently, the efficiency of this mode reaches only a fraction of percent because of the precursor ion selection step during which all other ions are rejected linked scan analysis. The aim of this project is (1) to build a new type of mass spectrometer for collecting linked scan spectra with efficiency close to 100% and (2) to implement this mass spectrometer for detecting and profiling modification sites on proteins. The construction of the mass spectrometer is based on a novel high ion capacity linear ion trap combined in a tandem configuration with a quadrupole collision cell and a quadrupole mass analyzer. The novel linear ion trap can store a large number of ions without degradation in performance because of space charge effects. All ions stored in the ion trap can be sequentially fragmented in the collision cell during the ejection process, but only particular ion fragments can be transmitted to the detector through the quadrupole mass analyzer whose scan is linked to the ion trap ejection scan. Thus, a linked scan spectrum can be obtained from all ions stored in the ion trap during a single scan of the instrument resulting in 100-1000 fold increase in efficiency of the device. This mass spectrometer can be used to detect modification sites on proteins with an unprecedented speed and sensitivity. It will have an immense value for monitoring particular products in the complex mixtures and,ultimately, for collecting fragmentation spectra from all observed species. When built, it will quickly become an indispensable research tool for advancement the frontiers of the biomedical research.