Anal Chem. 2010 Jan 1;82(1):23-7. doi: 10.1021/ac902120k.
Multiple reaction monitoring tandem mass spectrometry becomes an important strategy for measuring protein targets in complex biomatrixes. Active chemical modification of peptides like phenylthiocarbamoylation has unique potential for improving the measurement. This potential is enabled by active participation of a modifying group in site-preferential dissociation of modified peptides, which produces certain fragment ions at very high yields and in a sequence-independent manner. In this work, a novel combination of energy-resolved mass spectrometry with substituent effect investigation is used to analyze important factors that control the specificity of the site-preferential dissociation of phenylthiocarbamoyl peptides. On the basis of the linear correlation between collision energy and the Hammett constant as well as computational studies, it is found that the initial enhanced capture of a mobile proton and the subsequent, site-directed intramolecular proton transfer are important to the high yields (approximately 70-90%) for producing two types of fragment ions of phenylthiocarbamoyl peptides: the modified b(1) ion and the complementary y(n-1) ion. This understanding will help the design of new modification reagents. When integrated with the throughput and the signal-enhancing potential of peptide modification, active chemical modification of peptides will significantly advance mass spectrometry-based, targeted proteome analysis.
多重反应监测串联质谱成为测量复杂生物基质中蛋白质靶标的重要策略。肽的活性化学修饰，如苯硫甲酰化，具有独特的潜力来改善测量。这种潜力是通过修饰基团的积极参与来实现的，它可以在优先的肽解离中产生特定的片段离子，以非常高的产率和序列无关的方式产生。在这项工作中，能量分辨质谱与取代基效应研究的新组合用于分析控制苯硫甲酰化肽优先位点解离特异性的重要因素。基于碰撞能与哈米特常数之间的线性相关性以及计算研究，发现初始增强捕获移动质子，以及随后的、定向的分子内质子转移，对于产生苯硫甲酰化肽的两种类型的片段离子（修饰后的 b(1) 离子和互补的 y(n-1) 离子）的高产率（约 70-90%）是重要的。这种理解将有助于新修饰试剂的设计。当与肽修饰的通量和信号增强潜力相结合时，肽的活性化学修饰将显著推进基于质谱的靶向蛋白质组分析。
