News & Events

When

Date - April 12, 2023
1:00 pm - 2:00 pm

What

M.S. Thesis
Department of Chemistry & Biochemistry
UNC Greensboro
Zhang Research Group

Title: “LC-MS Analysis of Gangliosides: Methods Development and Software Solutions”

Abstract:

Gangliosides are high molecular weight, specialized metabolites found at greatest concentration in the central nervous system.  They are glycosphingolipids, possessing a nonpolar ceramide tail and a polar carbohydrate or ‘glycan’ head.  Ganglioside amphiphilicity is essential to their function as membrane lipids and to the formation of lipid rafts on cell surfaces.  This amphiphilicity also complicates their separation and analysis.  Gangliosides possess several forms of isomerism with isomers coeluting in reverse phase liquid chromatography.  Despite these difficulties and biological scarcity, ganglioside analysis is a growing field for their suspected role in various cancers, neurodegenerative disorders, and Type 1 Diabetes (T1D).

Although gangliosides can be analyzed directly using tandem mass spectrometry for their ceramides in the positive ion mode and for their glycans in the negative ion mode, chemical derivatization enhances structural identification through improved fragmentation while also enabling more sophisticated analytical techniques, such as methods based on isotopic and isobaric labeling.  With these methods in their infancy for comparative lipidomics, there is little compatible analysis software.  We have developed two stable-isotope analysis methods and three companion Python programs, one method based on amide formation and isotopic labeling, the second based on oxime formation and isobaric labeling.  From a normal mouse brain, the cerebellum, pons/medulla, midbrain, and cortex were dissected, homogenized, and their gangliosides extracted.  Both derivatization methodologies were applied to extracts representing 2 mg of tissue, cross-examining the brain regions with 79 gangliosides analyzed across 10 glycan classes.  This work greatly expands ganglioside analysis capacity in biological samples and can be applied to study of lipidome remodeling in T1D mice models.