Mass spectrometry analysis of carbohydrate and cholesteryl ester

Jia Ren, Purdue University

Abstract

Mass spectrometry (MS) has been established as the key method for glycan analysis by providing detailed structural information. Recently, we have demonstrated linkage and stereo-structure characterization of individual sugar units within linear oligosaccharides from MSn (n>2) CID of diagnostic ions which are generated from overlapping disaccharide units. However, structural elucidation of branched oligosaccharides is challenging based on this “top-down” approach, since disaccharide unit isomers can be produced upon gasphase dissociation from the branched structures. In this work, we combine microwave-assisted partial acid hydrolysis and HPLC separation to obtain structurally pure di- or tri-saccharides before MS analysis. MS n of these smaller units are used to provide linkage and stereo-structure of individual sugar units of branched oligosaccharides. The analysis of cholesteryl esters (CEs) in the context of shotgun lipidomics faces several challenges including their low response via electrospray ionization (ESI) and the existence the isomeric mixtures which differ in the location of carbon-carbon double bond (C=C) within the acyl chain. Existing studies typically utilize lithium or ammonium adducts of CE to facilitate better ionization and quantitation via positive mode ESI-tandem mass spectrometry (MS/MS); however, the location of C=C cannot be determined. In this study, we demonstrated the identification and quantitation of unsaturated CEs from human plasma including their C=C location information via coupling Paternò-Büchi (PB) reaction with nanoelectrospray (nanoESI)-MS/MS.

Degree

M.S.

Advisors

Xia, Purdue University.

Subject Area

Chemistry|Analytical chemistry

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