Structural glycans

The terminal oligosaccharide structures (glycans) in glycoconjugates which are associated with the eucaryotic cell represent specific contact and recognition sites for other cells, microorganisms, viruses, proteins, hormones and toxins. 

Some of the multibranched complex glycans of hen ovomucoid have been analyzed by f.a.b.-m.s. together with e.i.-m.s. These glycans exhibit exceptional structural features, because their mannotriose core can be highly substituted, as shown in 25. All samples gave abundant [M+Na]" ions when analyzed as their permethylated alditols, and this permitted the... 

Matsuda, K., Takahashi, N., Tsukamoto, Y., Honma, H., and Kohri, K., N-glycan structures of osteopontin from human bone, Biochem. Biophys. Res. Commun., 268, 814, 2000. 

Yuen, C.T., Stoning, P.L., Tiplady, R.J. et al. (2003) Relationships between the A-glycan structures and biological activities of recombinant human erythropoietins produced using different culture conditions and purification procedures. British Journal of Haematology, 121 (3), 511-526. 

Khoo, K-H., Morris, H.R. and Dell, A. (1993) Structural characterisation of the major glycans of Toxocara canis ES antigens. In Lewis, J. and Maizels, R.M. (eds) Toxocara and Toxocariasis Clinical, Epidemiological and Molecular Perspectives. Institute of Biology, London, pp. 133-140. 

A fourth family of A-glycans are referred to as hybrid glycans. These glycans share structural features of the high mannose and complex-type families. They usually retain two mannoses on the 6-arm of the trimannosyl core whilst complex-type antennae are elaborated on the 3-arm. Hybrid structures are frequentiy bisected and may also be core fucosylated (Fig. 15.1). It should be noted that whilst core fucosylation is common in complex-type, hybrid and truncated glycans, it is rarely found in high mannose glycans. 

Fig. 15.3. Structures of the four most commonly observed O-glycan cores.

Novel Fucosylated A/-glycan Core Structures in Haemonchus contortus... 

Fig. 15.5. Structures of A/-linked glycans from several different species of parasitic nematodes, illustrating both similarities with mammalian glycans (compare with Figs 15.1 and 15.2) and features unique to nematodes (e.g. tyvelose and PC capping and novel core fucosylation). The filarial nematode glycans are believed to be substituted with charged residues, which are not yet characterized.

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