Specific Cleavage at Peptide Backbone C_α-C and CO-N Bonds during MALDI-ISD Mass Spectrometry with 5-nitrosalicylic Acid as the Matrix
Specific Cleavage at Peptide Backbone C_α-C and CO-N Bonds during MALDI-ISD Mass Spectrometry with 5-nitrosalicylic Acid as the Matrix
复制标题
以 5-硝基水杨酸为基质的 MALDI-ISD 质谱中肽主链 C_α-C 和 CO-N 键的特异性裂解
DOI：
10.1002/rcm.5130
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
M.Takayama
中科院分区：
文献类型：
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作者：
D.Asakawa;M.Takayama
本文描述了在基质辅助激光解吸/电离(MALDI)过程中，使用5-硝基水杨酸(5-NSA)作为多肽的源内衰变(ISD)的基质。从机理上讲，衰变过程是由5-NSA从多肽主链酰胺氮中提取氢而开始的。氢提取导致形成含有自由基酰胺氮的氧化肽。随后，将Cα-C键的N端裂解到多肽键上，形成Ana·/x片段对。与其他残基相比，甘氨酸残基上的C-α-C键更不容易被切割。Cα-C键与Pro和SAR残基的N-末端不会被上述机制切割；相反，从Pro或SAR Cα-H键上抽氢后，N-末端与Pro的肽键被切割成b-andy-系列离子。我们还表明，MALDI5-NSA诱导的ISD产生的碎片是独立于电离过程形成的。版权所有©2011 John Wiley&Sons，Ltd.
The use of 5‐nitrosalicylic acid (5‐NSA) as a matrix for in‐source decay (ISD) of peptides during matrix‐assisted laser desorption/ionization (MALDI) is described herein. Mechanistically, the decay process is initiated by a hydrogen abstraction from a peptide backbone amide nitrogen by 5‐NSA. Hydrogen abstraction results in formation of an oxidized peptide containing a radical amide nitrogen. Subsequently, the Cα–C bond N‐terminal to the peptide bond is cleaved to form ana·/xfragment pair. The Cα–C bonds C‐terminal to Gly residues were less susceptible to cleavage than were those of other residues. Cα–C bonds N‐terminal to Pro and Sar residues were not cleaved by the aforementioned mechanism; instead, after hydrogen abstraction from a Pro or Sar Cα–H bond, the peptide bond N‐terminal to the Pro was cleaved yieldingb‐ andy‐series ions. We also show that fragments produced by MALDI 5‐NSA‐induced ISD were formed independently of the ionization process. Copyright © 2011 John Wiley & Sons, Ltd.