In attempts to explore the usefulness of the newly introduced electron capture dissociation (ECD) mass spectrometry for structural analysis of peptides/proteins, different fundamental aspects of the ECD method were investigated using a combination of controlled experiments and high-level theoretical calculations. The relative propensity for dissociation (RPD) of different amino acid residues were extracted from a series of ECD experiments using a common peptide model of RGGGXGGGR, where X was varied systematically among 20 common amino acid residues. Although polar and aromatic amino acid residues were found to behave differently, there exists a fair correlation between the experimental RPD values of aliphatic amino acid residues and the corresponding calculated hydrogen atom affinities of the nearby carbonyl groups. The existence of this correlation reinforces the importance of "hot hydrogen-atom model". From the same set of experiments, the side chain loss reactions of the reduced precursor ions and the zn+• species were extracted. To account for the observed secondary fragments, several generalized dissociation pathways were proposed. The energetics of these dissociation pathways were evaluated theoretically with truncated peptide models using ab initio and DFT calculations; and the kinetics of several competitive reactions were evaluated using Rice-Ramsberger-Kassel-Marcus (RRKM) calculations. / The effect of charge carriers on ECD of peptides/proteins was also studied. Peptides charged through protonation of different basic amino acid residues were found to give ECD spectra of different complexities. The formation of b-/y- and atypical internal fragment ions in peptides with histidines (and lysine, to a lesser extent) as proton carriers was attributed to the higher electron-proton recombination energy as revealed from the energy cycle diagram. Peptides charged through attachment of divalent metal ions were found to give very different ECD spectra. It was believed that typical c/z • fragments were formed from neutralization reactions involving electron-proton recombination; whereas a/b/y fragments were formed from reaction involving electron-metal ion recombination. The preference of recombination channels was somehow related to the electronic configurations of the divalent metal ions. / Fung Yi Man. / "July 2006." / Adviser: T. W. Chan. / Source: Dissertation Abstracts International, Volume: 68-08, Section: B, page: 5254. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 180-185). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_343813 |
| Date | January 2006 |
| Contributors | Fung, Yi Man., 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 (xii, 213 p. : ill.) |
| Coverage | Analysis, Analysis |
| 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/) |
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