High Efficiency Linked Scan Mass Spectrometer

描述(由申请人提供)：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作用的先决条件。尽管在使用几种技术，如射线照相术、埃德曼测序和免疫化学来揭示修饰方面取得了一定的成功，但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在这项任务中发挥越来越重要的作用。几种类型的质谱计的联动扫描操作模式显示了检测和分析几种类型的修改的特殊前景。这项技术具有很高的选择性，是基于在化合物的碎片光谱中观察到特定特征片段的一致性。目前，这种模式的效率仅达到几分之一，这是因为前驱体离子选择步骤，在此过程中所有其他离子都被拒绝链接扫描分析。该项目的目标是(1)建立一种新型的质谱仪，用于收集连接扫描光谱，效率接近100%；(2)实现这种质谱仪，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容量线性离子陷阱，它由四极碰撞池和四极质量分析器串联而成。这种新型的线性离子陷阱可以存储大量的离子，而不会因为空间电荷效应而导致性能下降。在喷射过程中，存储在离子陷阱中的所有离子都可以顺序地在碰撞池中碎裂，但只有特定的离子碎片可以通过四极质量分析器传输到探测器，该四极质量分析器的扫描与离子陷阱喷射扫描相连。因此，在仪器的一次扫描过程中，可以从离子陷阱中存储的所有离子获得链接扫描光谱，从而使设备的效率提高100-1000倍。这种质谱仪可以用来以前所未有的速度和灵敏度检测蛋白质的修饰位点。它将对监测复杂混合物中的特定产物，并最终收集所有观察到的物种的碎片光谱具有巨大的价值。建成后，它将迅速成为推进生物医学研究前沿不可或缺的研究工具。

DESCRIPTION (provided by applicant): 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 percent 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.