title: Investigation of c ions formed by N-terminally charged peptides upon collision-induced dissociation.
abstract: 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.
authors.affiliation: College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.affiliation: College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China.
authors.forename: Jinrong
authors.initials: J
authors.lastname: Liu
authors.affiliation: College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China.
authors.forename: Jungang
authors.initials: J
authors.lastname: Cao
authors.affiliation: College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China.
authors.forename: Huixin
authors.initials: H
authors.lastname: Wang
authors.affiliation: College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China.
authors.forename: Xinshu
authors.initials: X
authors.lastname: Guan
authors.affiliation: College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China.
authors.forename: Zhonglin
authors.initials: Z
authors.lastname: Wei
authors.affiliation: College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China. guoxh@jlu.edu.cn.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Guo
mesh_terms: D000595:Amino Acid Sequence; D003903:Deuterium; D007477:Ions / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D011522:Protons; D053719:Tandem Mass Spectrometry
chemical_list: D007477:Ions; D010446:Peptide Fragments; D010455:Peptides; D011522:Protons; D003903:Deuterium
keywords: McLafferty-type rearrangement; c ions; charge-remote; fixed-charge; peptide fragmentation