Tandem mass spectrometric analyses of novel synthetic neoglycolipids and amphiphilic carbohydrate molecules

Vaillant, Celine (2008) Tandem mass spectrometric analyses of novel synthetic neoglycolipids and amphiphilic carbohydrate molecules. Masters thesis, Memorial University of Newfoundland.

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Abstract

This thesis describes the mass spectrometric and low-energy induced collision analyses of the protonated molecules obtained from a series of novel synthetic amphiphilic neoglycolipid cholesteryl derivatives using electrospray ionization. It also confirms the in situ internal elimination of the polyethoxy-spacer linkers occurring with the simultaneous formation of a C-glycoside ion-species produced by an intramolecular complex ion-molecule reaction occurring in the ionization source interface and in the collision cell of the tandem mass spectrometer. -- The novel series of synthetic neoglycolipids described in this thesis varied in size and composition. They were composed of a similar cholesterol (hydrophobic) head covalently attached to a variable length of different polyethoxy spacers, covalcntly linked to a polar carbohydrate (hydrophilic) head such as 2-acetamido-2-deoxy-β-D-glucopyranosyl or 2-azido-2-deoxy-β-D-glucopyranosyl units. -- The novel formation of a different type of [C-glycoside+H-N₂]⁺ ion-species formed during the ESI-MS and ESI-MS/MS analyses of the neoglycolipid series containing the 2-azido-2-deoxy-glucopyranosyl moiety is also described in this thesis. The difference in the chemical structures of neoglycolipids affects the low-energy induced collision fragmentation and the abundance of the resulting product ions. Data on diastereisomers, anomers and constitutional isomers of the neoglycolipids fragmentation were compared to verify the presence of the C-glycoside ion species. -- Finally, the analyses of a series of new synthetic simple glycolipids, N-acetyl-glycosides and N-glycoside derivatives, which do not contain the cholesteryl aglycon portion, were carried out to determine the fragmentation pathway and to observe the similarity with the fragmentation pathway of the carbohydrate portion of the studied neoglycolipids.

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