Hot Hydrogen Atom Irradiation of Protonated/Deprotonated Peptide in an Ion Trap Facilitates Fragmentation through Heated Radical Formation
Hot Hydrogen Atom Irradiation of Protonated/Deprotonated Peptide in an Ion Trap Facilitates Fragmentation through Heated Radical Formation
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DOI：
10.1021/jacs.1c11081
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发表时间：
2022-02-23
影响因子：
15
通讯作者：
Tanaka, Koichi
中科院分区：
文献类型：
--
作者：
Asakawa, Daiki;Takahashi, Hidenori;Tanaka, Koichi
涉及与氢原子反应的裂解串联质谱法有望用于肽和蛋白质的分析。一般来说，氢原子优先与奇电子自由基反应。由于偶电子肽离子与氢原子的反应速率较低，几乎观察不到氢原子与偶电子肽离子的结合。到目前为止，只有我们小组开发的方法成功地通过与氢原子反应诱导了偶电子肽离子的裂解。在本研究中，我们关注离子阱质谱仪中肽离子和氢原子的温度，以了解相应反应的机制。因为偶电子肽离子和氢原子之间的反应存在显著的过渡态势垒，所以需要使用热氢原子来引发反应。该反应有助于增加生成的肽自由基的内能，因为反应热和氢原子的动能都转化为产物的内能。生成的以氧和碳为中心的肽自由基分别在亚皮秒和亚毫秒时间尺度上发生自由基诱导的裂解。
Tandem mass spectrometry with fragmentation involving the reaction with hydrogen atoms is expected to be useful for the analysis of peptides and proteins. In general, hydrogen atoms preferentially react with odd-electron radicals. The attachment of hydrogen atoms to even-electron peptide ions is barely observed because of their low reaction rate. To date, only the methodology developed by our group has successfully induced the fragmentation of even-electron peptide ions by reacting with hydrogen atoms. In the present study, we focused on the temperature of the peptide ions and hydrogen atoms in an ion trap mass spectrometer to understand the mechanism of the corresponding reaction. Because the reaction between even-electron peptide ions and hydrogen atoms has a significant transition state barrier, the use of hot hydrogen atoms is required to initiate the reaction. The reaction contributes to increase the internal energy of the resultant peptide radicals because the heat of reaction and kinetic energy of the hydrogen atom are converted to the internal energy of the product. The resultant oxygen- and carbon-centered peptide radicals undergo radical-induced fragmentation with sub-picosecond and sub-millisecond time scales, respectively.