Determination of sulfation pattern in brain glycosaminoglycans by chip-based electrospray ionization ion trap mass spectrometry

• DOI: 10.1007/s00216-009-3167-0
• Publication Date: 2009-10-13T11:17:05Z
• Authors: Corina Flangea; Catalin Schiopu; Eugen Sisu; Alina Serb; Michael Przybylski; Daniela G. Seidler; Alina D. Zamfir
• Keywords: Spectrometry, Mass, Electrospray Ionization; 0303 health sciences; Mouse brain; info:eu-repo/classification/ddc/540; Sulfates; Chondroitin Sulfates; Brain; Dermatan Sulfate; Disaccharides; Mice, Inbred C57BL; Mice; 03 medical and health sciences; Chondroitin/dermatan sulfate; Animals; Nanotechnology; Fully automated chip-based nanoelectrospray; Ion trap mass spectrometry; Glycosaminoglycans

Chondroitin sulfate (CS) and dermatan sulfate (DS) glycosaminoglycans display variability of sulfation in their constituent disaccharide repeats during chain elongation. Since a large proportion of the extracellular matrix of the central nervous system (CNS) is composed of proteoglycans, CS/DS disaccharide degree and profile of sulfation play important roles in the functional diversity of neurons, brain development, and some of its pathological states. To investigate the sulfation pattern of CS/DS structures expressed in CNS, we introduced here a novel method based on an advanced system encompassing fully automated chip nanoelectrospray ionization (nanoESI) in the negative ion mode and high capacity ion trap multistage mass spectrometry (MS(2)-MS(3)) by collision-induced dissociation (CID). This method, introduced here for the first time in glycomics of brain glycosaminoglycans, was particularly applied to structural investigation of disaccharides obtained by beta-elimination and digestion with chondroitin B and AC I lyase of hybrid CS/DS chains from wild-type mouse brain. Screening in the chip-MS mode of DS disaccharide fraction resulting after depolymerization with chondroitin B lyase revealed molecular ions assigned to monosulfated disaccharide species having a composition of 4,5-Delta-[IdoA-GalNAc]. By optimized CID MS(2)-MS(3), fragment ions supporting the localization of sulfate ester group at C4 within GalNAc were produced. Chip ESI MS profiling of CS disaccharide fraction obtained by depolymerization of the same CS/DS chain using chondroitin AC I lyase indicated the occurrence of mono- and bisulfated 4,5-Delta-[GlcA-GalNAc]. The site of oversulfation was determined by MS(2)-MS(3), which provided sequence patterns consistent with a rare GlcA-3-sulfate-GalNAc-6-sulfate structural motif. Figure Mouse brain GlcA-3-sulfate-GalNAc-6-sulfate structural motif.