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A variety of research projects involving mass spectrometry (MS) are under way in our laboratory. Specifically, using electrospray ionization (ESI), a new ionization technique which allows pre existing ions in solution to be transferred to gas phase with limited fragmentation. Coupling ESI to a mass spectrometer allows the detection of ions that are present in solution. We are investigating complexes between cyclodextrin host and a variety of guest molecules ranging from metal ions to proteins. These studies give evidence that the non covalent complexes of nucleosides and nucleobases with cyclodextrins formed in solution can be preserved, ionized and detected using ESI MS. The first research priority of our laboratory is to establish the mass spectrometric conditions necessary to characterize cyclodextrin-nucleoside/nucleobase complexes. The second stage of the research involves establishing the rules for fragmentation for characterizing the host-guest complexes between cyclodextrins and nucleosides/nucleobases. We will also use solution-phase and gas-phase H/D exchange in combination with ESI-MS and ESI-MS/MS to study cyclodextrin-nucleoside/nucleobase systems to obtain information about the specific interactions between the host and guest molecules. Another area of our research is focused on to understanding the changes that occur to GSH upon binding to metal ions. It has been proposed that reactive metal ions such as Cu (II) and Fe (III) readily catalyze oxidation of glutathione (GSH) and during these reactions there is formation of thiyl and hydroxyl species. These species are thought to be responsible for DNA cleavages. The proposed MS study will aid in: (1) characterizing metal GSH complexes, (2) determining the GSH residue responsible for binding a specific metal and (3) finding the metals that promote oxidation of GSH. |