During the course of the systematic study, it was also discovered that doubly-protonated diarginated peptides containing multiple glutamic acid residues (E) (n>4) could suppress the backbone fragmentation of [M+2H]+· . Together with the results obtained from conformational searches, it was hypothesized that the interactions between carboxylic oxygens of E side chains and backbone amide hydrogens could stabilize the radical intermediate and thereby inhibiting the usual N-Calpha cleavages and H · loss from [M+2H]+·. / In order to ascertain the impacts of the structural features of polypeptide and oligosaccharide ions on the dissociation of these biomolecules under typical collision induced dissociation (CID) and electron capture dissociation (ECD) conditions, the dissociation patterns of even-electron precursor ions generated by protonation ([M+nH]n+)/metalation ([Metal+M]n+), odd-electron hydrogen-deficient precursor ions (M+·) generated by SORI-CID of [Cu(Tpy)M]2+ and odd-electron hydrogen-surplus precursor ions ([M+2H]+·) generated by ECD of [M+2H] 2+ were examined. It was found that backbone cleavages, with the generation of b/y and c/z ions, were dominant in the dissociation of [M+H]+ and [M+2H]+· respectively. Whilst in the dissociation of M+·, side chain loss reactions were the major fragments generated. For post translational modification (PTM)-containing peptides, the labile PTM groups were found to cleave preferentially in the dissociation of M+· and [M+H]+, but were found to be retained in the intact peptides and peptide fragments in the dissociation of [M+2H]+·. It is hypothesized that the different dissociation pathways is attributed to the different nature of radicals. Further to these, it was found that in the dissociation of oligosaccharides, similar cleavage patterns (glycosidic and cross-ring cleavages) were obtained regardless of the nature of the precursor ions (i.e. whether odd- or even-electron) and the ion activation conditions. / Chan, Wai Yi. / Adviser: T.W. Dominic Chan. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 145-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344718 |
| Date | January 2010 |
| Contributors | Chan, Wai Yi, Chinese University of Hong Kong Graduate School. Division of Chemistry. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xvi, 164 leaves : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
Page generated in 0.0017 seconds