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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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Prof. Jonathan Amster, University of Georgia
Cracking the Glycan Code - A Mass Spectrometry Success Story
School Colloquium
Glycosaminoglycans (GAGs) are an important class of carbohydrates that play a central role in a number of biological processes, and their structural analysis is a target of substantial research effort [1]. Taken as a whole, glycosaminoglycans (GAGs) represent a challenging class of molecules to analyze due to their heterogeneity, the lability of sulfation modifications and the difficulty of distinguishing subtle structural differences, such as uronic acid stereochemistry. The last few years has seen considerable progress in GAG analysis by mass spectrometry with the introduction of supercharging methods for stabilizing sites of sulfation [2], chemical modification methods to replace sulfates with more stable functional groups [3], and novel methods of ion activation, such as electron detachment dissociation (EDD) [4]. We have investigated the applicability of EDD for fully characterizing several classes of GAGs with a single stage of tandem mass spectrometry. EDD has shown great utility for analyzing oligosaccharides from chondroitin/dermatan sulfate, heparan sulfate, and heparin. Generally speaking, EDD provides more structural detail than more widely used ion activation methods such as collision induced dissociation (CID) or infrared multiphoton photodissociation (IRMPD), and is less likely to lead to sulfate decomposition. Recently found that CID is useful for GAG analysis under selected circumstances. Specifically, CID has been useful for the analysis of full-length chondroitin sulfate saccharides from bikunin, for which the degree of sulfation is low compared to the degree of polymerization (0.3 sulfates per disaccharide repeat) [4]. Highly sulfated heparins have remained the most challenging of all GAG oligosaccharides to analyze. Surprisingly, we have recently found that CID is useful for this challenging class of GAGs if all of the ionizable protons are replaced by sodium ions [5]. The evolution of tandem mass spectrometry approaches for GAG analysis, and their application to the discovery of a consensus pattern of sulfation in proteoglycans will be presented.
References
[1] L.Y. Li, M. Ly, R.J. Linhardt, Proteoglycan sequence, Mol Biosyst, 8 (2012) 1613-1625.
[2] Y. Huang, X.F. Shi, X. Yu, N. Leymarie, G.O. Staples, H.F. Yin, K. Killeen, J. Zaia, Improved Liquid Chromatography-MS/MS of Heparan Sulfate Oligosaccharides via Chip-Based Pulsed Makeup Flow, Anal Chem, 83 (2011) 8222-8229.
[3] R.R. Huang, V.H. Pomin, J.S. Sharp, LC-MS (n) Analysis of Isomeric Chondroitin Sulfate Oligosaccharides Using a Chemical Derivatization Strategy, J Am Soc Mass Spectr, 22 (2011) 1577-1587.
[4] J.J. Wolff, I.J. Amster, L. Chi, R.J. Linhardt, Electron Detachment Dissociation of Glycosaminoglycan Tetrasaccharides, J. Am. Soc. Mass. Spectrom., 18 (2007) 234-244.
[5] M.J. Kailemia, L.Y. Li, M. Ly, R.J. Linhardt, I.J. Amster, Complete Mass Spectral Characterization of a Synthetic Ultralow-Molecular-Weight Heparin Using Collision-Induced Dissociation, Anal Chem, 84 (2012) 5475-5478.
For more information contact Prof. Facundo Fernandez (404-385-4432).
Website: Prof. Jonathan Amster
