Investigation of c ions formed by N-terminally charged peptides upon collision-induced dissociation.
Investigation of c ions formed by N-terminally charged peptides upon collision-induced dissociation.
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DOI：
10.1002/jms.3841
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发表时间：
2016-11
期刊：
影响因子：
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通讯作者：
B. Wang;Jinrong Liu;Jungang Cao;Huixin Wang;X. Guan;Zhonglin Wei;Xinhua Guo
中科院分区：
文献类型：
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作者：
B. Wang;Jinrong Liu;Jungang Cao;Huixin Wang;X. Guan;Zhonglin Wei;Xinhua Guo
由低能碰撞诱导解离产生的b和y序列离子等多肽片段通常被用于基于串联质谱仪(MS/MS)的多肽/蛋白质鉴定。潜在的形成机制已被广泛研究，并在文献中进行了描述。因此，建立了“移动质子模型”和“竞争路径模型”来解释大多数多肽的裂解行为。然而，MS/MS谱图中偶尔会出现涉及不熟悉的裂解途径或各种重排反应的不寻常的多肽片段，导致对MS/MS的解释混乱。在这项工作中，在低能碰撞诱导解离过程中，在含有N-末端精氨酸或重铁血红素基团的模型多肽的MS/MS谱中检测到一系列陌生的C离子。质子化的精氨酸基和亚铁血红素基团在远离裂解位的N-末端保持正电荷方面都起着重要作用。根据以前的报道和我们对氨基酸取代和氢-氚交换的研究，我们提出了麦克拉弗蒂型电荷远程碎裂重排作为解释前体多肽离子或非常规b离子形成c离子的潜在机制。密度泛函理论计算也被用来解释所提出的碎裂机制。版权所有©2016 John Wiley&Sons，Ltd.
Peptide fragments such as b and y sequence ions generated upon low-energy collision-induced dissociation have been routinely used for tandem mass spectrometry (MS/MS)-based peptide/protein identification. The underlying formation mechanisms have been studied extensively and described within the literature. As a result, the 'mobile proton model' and 'pathways in competition model' have been built to interpret a majority of peptide fragmentation behavior. However, unusual peptide fragments which involve unfamiliar fragmentation pathways or various rearrangement reactions occasionally appear in MS/MS spectra, resulting in confused MS/MS interpretations. In this work, a series of unfamiliar c ions are detected in MS/MS spectra of the model peptides having an N-terminal Arg or deuterohemin group upon low-energy collision-induced dissociation process. Both the protonated Arg and deuterohemin group play an important role in retention of a positive charge at the N-terminus that is remote from the cleavage sites. According to previous reports and our studies involving amino acid substitutions and hydrogen-deuterium exchange, we propose a McLafferty-type rearrangement via charge-remote fragmentation as the potential mechanism to explain the formation of c ions from precursor peptide ions or unconventional b ions. Density functional theory calculations are also employed in order to elucidate the proposed fragmentation mechanisms. Copyright © 2016 John Wiley & Sons, Ltd.