Xin Tong

Date of Award


Degree Type


Degree Name

Master of Science




Dr. Lars Konermann


Protein structure, folding and conformational dynamics are critical to understanding biological processes and biochemical reactions. In this work, electrospray ionization mass spectrometry (ESI-MS) combined with a γ-ray-mediated covalent labelling method is used to probe the structure of proteins. ∙OH radicals generated by γ- rays react with solvent-exposed amino acid side chains, which leads to multiple +16 Da shifts in the mass distribution of the protein. This thesis explores the relationship between oxidative labelling and protein concentration, and it investigates how changes in protein conformation affect the overall oxidation level. Using myoglobin as model system, it is demonstrated that the reactions of proteins with ∙OH radicals can be approximated as a pseudo-first order process, and that the level of oxidative labelling depends strongly on the protein concentration. Our results reveal that ∙OH labelling is less sensitive than H/D exchange for monitoring protein structural changes. In addition, control experiments employing a peptide (bradykinin) indicate that secondary factors can affect the degree of oxidative labelling without being related to protein conformational changes. It is concluded the -OH labelling is a viable probe for studying large-scale protein conformational changes, but only under conditions where secondary effects have been minimized.



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