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Title: Protein complexes in the gas phase : structural insights from ion mobility-mass spectrometry and computational modelling
Author: Hall, Zoe Lauren
ISNI:       0000 0004 2747 6789
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2013
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Structure determination of macromolecular protein assemblies remains a challenge for well-established experimental methods. In this thesis, an emerging structural technique, ion mobility-mass spectrometry (IM-MS) is explored. An assessment of collision cross section (CCS) measurement accuracy using travelling-wave IM (TWIMS) instrumentation was carried out (Chapter 3). Through the collation of a protein complex CCS database and the development of a calibration framework for TWIMS, significant improvements to CCS measurement accuracy have been achieved. Next, the advantages and limitations of using IM-MS to generate restraints for structure characterisation were explored. Computational tools designed to exploit IM-MS data for structural modelling were developed and tested on a training set of systems (Chapter 4). These include two heteromeric protein complexes, and an oligomeric intermediate involved in beta-2-microglobulin aggregation. Further structural information can be attained by using gas-phase dissociation techniques, such as collision-induced dissociation (CID). The effects of charge state on CCS and the gas-phase dissociation pathway of complexes were investigated (Chapter 5). This highlighted the possibility of using CID in conjunction with supercharging to manipulate dissociation pathways to achieve more useful structural information. Finally, the gas-phase structures of globular and intrinsically disordered protein complexes were probed by IM-MS and molecular dynamics (MD) simulations (Chapter 6). Experimental observations were recapitulated remarkably closely by simulations, including gas-phase structural collapse and the ejection of monomer subunits when the energy of the system was increased sufficiently. Overall, this research has contributed to the IM-MS field by providing the framework for improved CCS measurements of large protein complexes and the use of restraints from IM-MS for structural modelling. Significantly, IM-MS has been used in combination with charge manipulation, CID and MD simulations to reveal further insights into the gas-phase structures, stabilities and dissociation pathways of multimeric protein complexes.
Supervisor: Robinson, Carol V. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Biophysical chemistry ; Protein chemistry ; ion mobility ; mass spectrometry ; protein complexes