Glycomics methods and tools

N-glycans can be enzymatically released PNGase F (Glycerol-free), Recombinant after which they can be derivatized by premethylation or fluorescence labeling (via reductive amination).
O-glycans can be chemically released (beta elimination, hydrazinolysis), converted to their alditols, or derivatized by permethylation.
Permethylation allows efficient ionization and the formation of fragments during collision-induced-dissociation (CID). Permethylation of isolated glycans facilitates tandem MS experiments, where detailed structural information can be obtained.
Alternatively, glycans can be labeled with fluorescent tags for sensitive detection and quantitation during liquid chromatography coupled with fluorescence detection (LC-FLD). These groups might also assist ionization for mass spectrometry (MS), or bear charges for capillary electrophoresis (CE).
Commonly used tags are 2-aminobenzamide (2AB), 2-aminobenzoic acid (2AA), procainamide (PCA), and 8-aminopyrene-1,3,6-trisulfonic acid (APTS, used in CE). These tags are introduced via reductive amination in the presence of an acid catalyst and a reducing agent.
Detailed structural analysis of released N-glycans is possible by a combination of LC-MS analysis, which identifies N-glycans by retention time and exact mass, coupled with exoglycosidase array analysis (N-Glycan Sequencing Kit E0577s).
O-glycan alditols can be also sequenced using exoglycosidase analysis.

References:

Mulloy, B., et al. (2017) Essentials of Glycobiology, Chapter 50. Structural Analysis of Glycans. PMID 28876844
Muchena, J. et al. (2014) Anal. Chem. 86(1): 196 - 212. PMID 24313268
Reinhold, V. et al. (2013) Mol. Cell Proteomics. 12(4):866-73. PMID 23438731

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