Chemical derivatization coupled with liquid chromatography and tandem mass spectrometry for structural sequencing of sulfated glycosaminoglycans
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Sulfated glycosaminoglycans (GAGs) are important carbohydrates that participate in essential biological activities by interacting with various proteins in the extracellular matrix. Structural characterization of these biomolecules is of great value to understand their functions, but also challenging due to their highly heterogeneous nature and the lability of the sulfate modifications. The work presented here describes a new method using chemical derivatization coupled with liquid chromatography and tandem mass spectrometry (LC-MS/MS) for structural characterization of two major classes of sulfated GAGs, chondroitin sulfate (CS) and heparan sulfate (HS)/heparin. By replacing the labile and strongly polar sulfate groups with much more stable and hydrophobic acetyl groups, the chemical derivatization method allows isomeric GAG oligosaccharides being separated by standard reversed phase capillary high performance LC and distinguished by their fragmentation patterns generated from conventional collision induced dissociation (CID) MS/MS. The method is successfully used for structural sequencing of CS and HS oligosaccharides, including most of common sulfation positional isomers as well as epimers, and its application in biological relevant cases is also investigated.