News & Events

Rodell Barrientos

Posted on May 1, 2019


Date - May 1, 2019
1:00 pm - 2:00 pm


PhD Defense
Faculty Advisor: Dr. Qibin Zhang
Talk Title: Innovative Methods to Advance the Analysis of Intact Glycolipids by Mass Spectrometry


Glycolipids, also termed glycosphingolipids, are biologically important glycoconjugates that play crucial roles in health and diseases. Abnormality associated with the metabolism of these molecules has been implicated in numerous diseases such as lysosomal storage, Parkinson’s, Alzheimer’s, among others. The specific role of glycolipids in these pathologies is only partly understood. Specifically, the role of the glycan head group and the lipid backbone in biology remains elusive but current knowledge revealed the importance of both features in biological processes. As such, analysis of these molecules at the intact structure level is greatly warranted. To advance this relatively underexplored research area, development of accurate, sensitive, reproducible, and potentially high-throughput methodologies is greatly needed. In this presentation, novel mass spectrometry (MS)-based methods such as ozone-induced dissociation mass spectrometry (OzID-MS), isobaric labeling, and differential isotope labeling will be discussed. OzID-MS allowed the determination of the location of carbon-carbon double bonds in intact, unsaturated glycolipids. Specifically, this method distinguished isomeric and isobaric species that are otherwise non-distinguishable using contemporary MS fragmentation techniques alone. Isobaric labeling when applied to sialic acid-containing glycolipids, not only allowed multiplexed analysis of these molecules but also increased the sensitivity and enabled structural determination of up to six independent samples in a single LC-MS/MS injection. Differential isotope labeling of glycolipids by permethylation has allowed at least ten-fold enhancement of ionization efficiency of glycolipids, aided straightforward elimination of contaminating phospholipids in the total lipids extract, and permitted accurate and reproducible quantification while providing useful MS/MS information to elucidate structure of unknown species. Finally, these methods were applied in a variety of matrices, including bovine brain, porcine brain, and cell extracts. Taken together, these methods are expected to contribute and advance intact glycolipids analysis in biological samples.