Tandem Mass Spectrometry Using the Atmospheric Pressure Electron Capture Dissociation Ion Source
Tandem Mass Spectrometry Using the Atmospheric Pressure Electron Capture Dissociation Ion Source
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DOI：
10.1021/ac5002959
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发表时间：
2014-05-06
影响因子：
7.4
通讯作者：
Blades, Michael W.
中科院分区：
文献类型：
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作者：
Robb, Damon B.;Brown, Jeffery M.;Blades, Michael W.
大气压电子捕获解离(AP-ECD)是一项新兴的技术，几乎可以应用于任何电喷雾质谱仪，而不需要对主要仪器进行修改。然而，到目前为止，由于电子捕获反应发生在离子源中，AP-ECD明显无法在裂解前选择前体，即无法进行串联质谱分析(MS/MS)实验。在本文中，我们展示了一种新的AP-ECD-MS/MS方法，该方法使用的AP-ECD源在Xevo G2-S四极飞行时间质谱仪上。这种方法利用了电子捕获反应产生电荷减少的“ECnoD”产物的趋势，这种产物已经俘获了一个电子，并断裂了一个共价键，但不会立即解离成单独的产物，因此保留了前体离子的质量。在该方法中，来自AP-ECD源的ECnoD产物在四极滤质器中被分离，并通过在碰撞池中的补充激活来诱导解离，然后使用高分辨率TOF对释放的ECD碎片离子进行质量分析。通过这种方式，即使源中的所有前驱体都平行地经历电子捕获反应，AP-ECD也可以获得真实的MS/MS光谱。在这里，使用一种不能执行基于电子的裂解的新型Q-TOF仪器，我们给出了一组模型多肽的AP-ECD-MS/MS结果，并表明利用该方法很容易获得信息丰富的高序列覆盖率的光谱。
Atmospheric pressure electron capture dissociation (AP-ECD) is an emerging technique capable of being adopted to virtually any electrospray mass spectrometer, without modification of the main instrument. To date, however, because the electron capture reactions occur in the ion source, AP-ECD has been limited by its apparent inability to select precursors prior to fragmentation, i.e., to perform tandem mass spectrometry (MS/MS) experiments. In this paper we demonstrate a novel AP-ECD-MS/MS method using an AP-ECD source on a Xevo G2-S quadrupole time-of-flight (Q-TOF) mass spectrometer from Waters Micromass. The method takes advantage of the tendency for electron capture reactions to generate charge-reduced "ECnoD" products, species that have captured an electron and have had a covalent bond cleaved yet do not immediately dissociate into separate products and so retain the mass of the precursor ion. In the method, ECnoD products from the AP-ECD source are isolated in the quadrupole mass filter and induced to dissociate through supplemental activation in the collision cell, and then the liberated ECD fragment ions are mass analyzed using the high-resolution TOF. In this manner, true MS/MS spectra may be obtained with AP-ECD even though all of the precursors in the source are subjected to electron capture reactions in parallel. Here, using a late-model Q-TOF instrument otherwise incapable of performing electron-based fragmentation, we present AP-ECD-MS/MS results for a group of model peptides and show that informative, high-sequence-coverage spectra are readily attainable with the method.