Products Cited in Publications Worldwide Study of the radiation-induced oxidation of molecules of biological interest by tandem mass spectrometry and IRMPD spectroscopy

Study of the radiation-induced oxidation of molecules of biological interest by tandem mass spectrometry and IRMPD spectroscopy

Jiang, Yining

Abstract

Reactive oxygen species (ROS) such as the hydroxyl radical (•OH) play important beneficial roles in biological processes, while their uncontrolled production and reactivity are determining factors in pathophysiology. In this thesis, I focused on the radiolytic oxidation of small model systems of biological interest. The methionine-containing peptides and the derivatives of DNA nucleobases were investigated. Both are susceptible to ROS and play a key role in the correct functioning of the body. Although the identification of the post-translational modifications (PTMs) in peptides and the oxidative lesions in DNA was achieved by various classical methods, the oxidation processes of these molecules are still not fully understood and little is known about the relationship between the radicals formed during oxidation and the final products. Infrared Multiple Photon Dissociation (IRMPD) spectroscopy is a widely used experimental method of probing the structures of ions in the gas phase. Tandem mass spectrometry (MS/MS) combined with IRMPD spectroscopy was employed in this thesis to investigate the diagnostic infrared spectral signatures of these oxidative modifications in different molecular systems and to better understand the hydroxyl radical-induced oxidation mechanisms. By combining with quantumchemical calculations, direct information on geometries of populated conformations can be obtained. Multiple factors involved in the Met oxidation process have been systematically investigated. DNA oxidative lesions have been successfully probed by IRMPD spectroscopy for gaining direct structural information.

Keywords

Methionine ; DNA ; radiolytic oxidation ; tandem mass spectrometry ; IRMPD spectroscopy

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