"Additional Roles of Ionization Technique in Method Development"
Professor Norman Chiu, University of North Carolina Greensboro, Department of Chemistry & Biochemistry
The development of the soft ionization techniques, namely electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI), are the game changers in the recent history of mass spectrometry. Owing to its simplicity, compatibility to liquid chromatography and availability in the commercial market, ESI and its related techniques have become the major ionization techniques in mass spectrometry. In order to address the analytical challenges in our research work, which exclude the efficiency of ion yield, the use of other ionization techniques have been explored. Our past and current efforts have led to the development of a number of simple methods for RNA analysis or high through screening of cellular toxicity by using mass spectrometry or ion mobility mass spectrometry.
"Novel Approaches for Comprehensive Characterization and Quantification of Glycosphingolipids"
Rodell Barrientos, Laboratory of Professor Qibin Zhang, University of North Carolina Greensboro, Department of Chemistry & Biochemistry
Glycosphingolipids are ubiquitous in the biological system and perturbation of its metabolism is often associated with human diseases. The function of these molecules relies both on the glycan and lipid structures thus they warrant to be determined as intact molecular species. While the glycan part has been extensively studied, the lipid portion, most notably the location of unsaturation remained relatively underexplored. In this presentation, two techniques will be presented: first is the gas-phase ozonolysis reaction termed ozone-induced dissociation (OzID) implemented in a traveling wave-based Quadrupole Time-of-Flight (Q-ToF) mass spectrometer, and second is the multiplexed LC-MS/MS based relative quantification of intact gangliosides. The use of OzID-MS not only enabled the determination of carbon-carbon double bond locations but also differentiated isobaric and isomeric species in a straightforward manner, which would have been difficult to identify using contemporary chromatography or fragmentation techniques alone. Moreover, we developed a novel approach for multiplexed quantification of intact gangliosides using carbonyl-reactive isobaric tandem mass tag (TMT) reagent. In contrast to traditional glycomics approach that requires prior deglycosylation step to enable the ligation of TMT, our method involves chemoselective oxidation of the sialic acid side chain to introduce an aldehyde group where the TMT reagent can be attached to. Using tandem mass spectrometry, reporter ion groups are cleaved off from the mass-selected precursor ion and their intensities reflect the relative amounts of analytes in the sample. With this strategy, both the glycan and lipid structures can be determined from up to six different samples simultaneously, in a single injection.