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Investigation of c ions formed by N‐terminally charged peptides upon collision‐induced dissociation
Author(s) -
Wang Bing,
Liu Jinrong,
Cao Jungang,
Wang Huixin,
Guan Xinshu,
Wei Zhonglin,
Guo Xinhua
Publication year - 2016
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.3841
Subject(s) - chemistry , fragmentation (computing) , dissociation (chemistry) , tandem mass spectrometry , collision induced dissociation , peptide , ion , protonation , mass spectrometry , mass spectrum , stereochemistry , chromatography , biochemistry , organic chemistry , computer science , operating system
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.