Capillary Zone Electrophoresis-Electrospray Ionization Tandem Mass Spectrometry for Total Analysis of Chondroitin/Dermatan Sulfate Oligosaccharides.

Abstract

Proteoglycans are heavily glycosylated proteins, covalently linked to one or more glycosaminoglycan (GAG) chains, abundantly expressed in the extracellular matrix (ECM). Among GAGs, chondroitin sulfate (CS) and dermatan sulfate (DS) play an essential role at the ECM level; however, the composition of the hybrid CS/DS as well as the distribution of the sulfate groups along the chain were also shown to influence biological activities in brain. The elevated structural diversity of CS/DS motifs, in which sulfation may occur at GalNAc and/or IdoA/GlcA in various combinations, requires the development of specific high performance analytical methods for reliable elucidation. Due to its sensitivity, reproducibility, and efficiency, capillary zone electrophoresis (CZE) for separation of CS/DS oligosaccharides coupled to electrospray ionization mass spectrometry (ESI-MS) for their structure determination contributed an essential progress to this field.In the present chapter, two powerful methods based on CZE for separation and ESI-MS for identification and structural analysis of CS/DS are presented. The first part is devoted to offline CZE-ESI-MS based on fraction collection, screening by negative ion mode nanoESI, and fragmentation analysis in tandem MS using collision-induced dissociation (CID) at low ion acceleration energies. In the second part of the chapter, a strategy for online CZE-ESI-MS in normal polarity and negative mode ESI followed by tandem MS in real-time data-dependent acquisition mode for CS/DS separation, screening, and fragmentation is described in detail. The latter method entails the in-laboratory manufacturing of a simple yet sturdy interface for the online CZE coupling to ESI-MS and the optimization of the coupled system for total analysis of regularly sulfated and irregularly, i.e., under- and oversulfated CS/DS domains.