title: Gas-phase fragmentation of [M+nH+OH]n•+ ions formed from peptides containing intra-molecular disulfide bonds.
abstract: In this study, we systematically investigated gas-phase fragmentation behavior of [M + nH + OH](n•+) ions formed from peptides containing intra-molecular disulfide bond. Backbone fragmentation and radical initiated neutral losses were observed as the two competing processes upon low energy collision-induced dissociation (CID). Their relative contribution was found to be affected by the charge state (n) of [M + nH + OH](n•+) ions and the means for activation, i.e., beam-type CID or ion trap CID. Radical initiated neutral losses were promoted in ion-trap CID and for lower charge states where mobile protons were limited. Beam-type CID and dissociation of higher charge states of [M + nH + OH](n•+) ions generally gave abundant backbone fragmentation, which was highly desirable for characterizing peptides containing disulfide bonds. The amount of sequence information obtained from CID of [M + nH + OH](n•+) ions was compared with that from CID of disulfide bond reduced peptides. For the 11 peptides studied herein, similar extent of sequence information was obtained from these two methods.
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing, People's Republic of China.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Ma
authors.forename: Chasity B
authors.initials: CB
authors.lastname: Love
authors.forename: Xinrong
authors.initials: X
authors.lastname: Zhang
authors.forename: Yu
authors.initials: Y
authors.lastname: Xia
mesh_terms: D000595:Amino Acid Sequence; D004220:Disulfides / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D020539:Sequence Analysis, Protein; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods*
chemical_list: D004220:Disulfides; D005740:Gases; D010455:Peptides