Human milk is a complex mixtures, partly consisting of over one hundred unique short chain sugars (oligosaccharides), which are referred to as HMOs. These HMOs are thought to be crucial in the development of the infant immune system. However, methods to isolate and study these sugars need improvement. Recently, advances in instrumentation and technique have allowed for development of better methods to correctly identify these saccharides for further studies. Successful identification will then help us better understand the importance of these trace compounds in human milk. This project looks at two isomeric saccharides, LSTc and LSTd. These two saccharides are made of the same five subunits and differ by only one linkage. Because they are made of the same subunits, MS fragmentation often results in identical fragments, which does not help us to distinguish them. A common method of generating unique fragments is to associate metal ions with the sugars. Differently structured isomers result in unique chelation strength, which can result in unique fragmenations. In this study, barium acetate is combined with the saccharides to create adducts that allow characteristic fragments to be formed from each isomer. Electron transfer is used to create singly charged species that can then be selected and these species are vibrationally activated. A fragmentation pathway is then proposed for each saccharide. Portions of the fragmentation pathway is then confirmed using Fourier transform - ion cyclotron resonance mass spectrometry (FT-ICR). Our techniques allows for precise selection of a specific fragment and generation of only the daughter fragments from the specifically selected fragment. This process was able to successfully confirm portions of the fragmentation pathway. This research has helped develop techniques for differentiating known oligosaccharide isomers. Fruther research will apply the technique we have developed to studying otther unique oligosaccharide, with the eventual goal of being able to analyze mixtures of unknowns and biological matrices.

Mass spectrometry fragmentation of barium adducted human milk oligosaccharides

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.