Glycans and Monosaccharides

Glycosylation is the most-common form of posttranslational modification found on proteins and is critical for a wide range of functions, including cell—cell interaction, immune defense, inflammation, and disease progression. Sugars are ideal for coding these complex 

---

The partially methylated monosaccharides obtained on depolymerization of the permethylated sample are preferably analyzed as acetates by g.l.c.-m.s., as shown by Bjomdal and coworkers.41,42 The neutral sugars and the amino sugars obtained in acetolysis-acid hydrolysis are reduced, and acetylated for the analysis, and the amino-hexitol and the neuraminic acid residues are acetylated after methanolysis. Identification with the aid of g.l.c.-m.s. has been described for all of the common components of protein- and lipid-linked glycans and oligosaccharides from animal cells, namely, the neutral sugars,41-43 hexitols,44 hexosamines,29,43,45,46 aminohexitols,31,32 and neuraminic acids.33,34,47... 

O-glycosidic, between the reducing end monosaccharide and the side chain hydroxy group of most commonly serine and threonine but also hydroxyproline, hydroxylysine, and tyrosine (O-glycans), and... 

MS provides measurement of the molecular weight for glycans. The saccharide composition for glycans released from glycoproteins (or glycolipids) can be determined based on the accurate mass, the structures of known N- or O-linked glycans, and the core structure, as well as the masses of the monosaccharides. In addition, tandem MS can confirm the proposed composition and provide further details of the structure. 

Information on the presence of N- or O-glycosylation, extent of glycosylation and monosaccharide composition of the glycan. 

---