High Efficiency Linked Scan Mass Spectrometer

翻译后修饰与细胞中蛋白质功能的调节密切相关。 检测蛋白质上修饰的存在并定量其丰度是 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， 作为放射照相术，Edman测序和免疫化学，以揭示修改，这项研究继续， 提出了艰巨的分析挑战。基于质谱的方法开始发挥作用， 在这项工作中发挥越来越重要的作用。几种类型质量块的联动扫描操作模式 光谱仪显示出用于检测和分析几种类型的修饰的特殊前景。的 该技术是高度选择性的，并且基于观察特定特征片段的一致性 在化合物的裂解光谱中。目前，这种模式的效率仅达到一小部分 因为在前体离子选择步骤期间，所有其他离子都被拒绝链接扫描， 分析.本课题的目的是（1）建立一种新型的质谱仪，用于收集链接扫描 效率接近100%的质谱，以及（2）实现该质谱仪用于检测和分析 蛋白质上的修饰位点。质谱计的结构是基于一种新型的高离子 与四极碰撞室和四极串联配置的电容线性离子阱 质量分析器新型线性离子阱可以存储大量离子而不会退化， 由于空间电荷效应。存储在离子阱中的所有离子可以被顺序地碎裂 在喷射过程中，在碰撞室中，但是只有特定的离子碎片可以被传输到碰撞室中。 通过四极质量分析器将离子阱注入检测器，四极质量分析器的扫描与离子阱喷射扫描相关联。因此 可以从存储在离子阱中的所有离子获得链接的扫描光谱 仪器，导致装置的效率增加100-1000倍。该质谱仪可以 用于以前所未有的速度和灵敏度检测蛋白质上的修饰位点。它将有一个 对于监测复杂混合物中的特定产品以及最终收集 所有观察到的物质的碎片光谱。一旦建成，它将迅速成为一个不可或缺的 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.