CCD-1095Sk

GAGDoMa: A High-Sensitivity Analytical Framework for Mapping the Glycosaminoglycome

Glycosaminoglycans (GAGs) are structurally diverse polysaccharides essential to numerous biological processes, yet comprehensive analysis of the "glycosaminoglycome" remains analytically challenging. To address this, Persson et al. developed GAGDoMa, a novel liquid chromatography-mass spectrometry (LC-MS) framework for high-resolution profiling of GAG oligosaccharides.

GAGDoMa employs bacterial lyases for controlled depolymerization: chondroitinase ABC fully degrades chondroitin sulfate/dermatan sulfate (CS/DS) into disaccharides and linkage-region structures, while chondroitinase AC and B cleave specifically at GlcA or IdoA residues, generating oligosaccharides of varying lengths. Heparinases selectively degrade heparan sulfate without affecting CS/DS. These eliminative reactions generate 4,5-unsaturated hexuronic acid (ΔHexA) residues, distinguishable by mass spectrometry from non-reducing end HexA residues (Δmass = 18.0106 Da) (Figure 1a). Xyloside-primed CS/DS was isolated from human breast fibroblasts (CCD-1095Sk) and breast carcinoma cells (HCC70), depolymerized, and analyzed using nanoflow reversed-phase ion-pairing (RPIP) chromatography with dibutylamine (DBA) as a volatile ion-pairing agent. Coupled to an LTQ Orbitrap Elite mass spectrometer in negative ionization mode, this setup achieved ~300-fold higher sensitivity and superior chromatographic resolution compared to previous microscale LC-MS/MS methods. Fragmentation was performed using stepped higher-energy collisional dissociation (HCD) at normalized collision energies (NCEs) of 20-80%, optimizing structural interpretation. Extracted ion chromatograms of the recurring precursor ion at m/z458.06-corresponding to internal oligosaccharides with one sulfate per disaccharide (dp2nSn)-revealed separation of species ranging from dp2S1 to dp16S8 (Figure 1b-d). Additionally sulfated oligosaccharides (dp2nSn+1) were detected and resolved chromatographically, despite in-source sulfate loss generating the same m/z458.06 signature (Figure 1e). Linkage-region structures (ΔL) containing the naphthyl aglycon were cleanly separated from internal oligosaccharides, enabling MS1-level identification (Figure 1f).

GAGDoMa enabled extensive compositional profiling of intact CS/DS, resolving species from L11S4 to L29S14 with mass accuracies <10 ppm. This framework provides unprecedented sensitivity and resolution for characterizing GAG structural diversity, offering a powerful tool for glycosaminoglycome mapping in biological and disease contexts.