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The radical ion chemistry of electron capture dissociation mass spectrometry of modified peptides

Jones, Andrew (2012)
Ph.D. thesis, University of Birmingham.

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Abstract

The introduction of electron capture dissociation mass spectrometry in 1998 has provided a unique technique for the analysis of peptides and proteins, especially for the identification and localisation of posttranslational modifications. Despite many successes debate continues on the radical-based mechanism of ECD. This thesis explores ECD behaviour in a wide range of PTMs with the intention of furthering our knowledge of the radical-based mechanism. Studies were undertaken on the effect of 3-nitrotyrosine, which is an electron withdrawing group, on ECD. The presence of nitration dramatically decreases peptide backbone sequence coverage but results in the presence of abundant small neutral losses. The key finding is the insight provided into the hierarchy of the various proposed ECD mechanisms. ECD of cysteine bound modifications is shown to result in the fragmentation of the sulfur-modification bond and backbone sequence coverage is highly diminished when analysing S-nitrosopeptides. ECD behaviour of hydrogen-deficient radical peptides is highly dependent on gas-phase peptide structure, with electron capture typically resulting in an increase in charge-reduced precursor intensity. Comparisons of the intermolecular phospho-guanidinium bond strengths between phospho-serine, -threonine and -tyrosine were undertaken. ECD of these complexes results in the retention of the noncovalent bond allowing backbone sequence coverage.

Type of Work:Ph.D. thesis.
Supervisor(s):Cooper , Helen
School/Faculty:Colleges (2008 onwards) > College of Life & Environmental Sciences
Department:School of Biosciences
Subjects:QD Chemistry
QH301 Biology
Institution:University of Birmingham
ID Code:3620
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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