Hybrid glycoproteins

FIGURE 9.26 The carbohydrate tnoiedes of glycoproteins may be linked to the protein via (a) serine or threonine residues (in the O-linked saccharides) or (b) asparagine residues (in the N-linked saccharides), (c) N-Linked glycoproteins are of three types high mannose, complex, and hybrid, the latter of which combines structures found in the high mannose and complex saccharides. 

The enzymatic synthesis of a hybrid type oligosaccharide on the hen ovalbumin with 13C-enriched galactose allowed the measurement of the 13C-NMR spectra of the whole glycoprotein and additionally, the determination of the correlation times of the protein and the oligosaccharide to 25 ns and 40-80 ns, respectively [168]. This implies that the carbohydrate, at least in its terminal monosaccharide constituents, has a much higher flexibility than the protein, and its flexibility is only little impeded by the attachment to the protein. 

L. M. Likhosherstov, V. E. Piskarev, N. F. Sepetov, V. A. Derevitskaya, and N. K. Kochetkov, Structure of the oligosaccharide chains of riboflavin-binding glycoprotein from hen egg white. 4. Neutral oligosaccharides of a hybrid type, Bioorg. Khim., 17 (1991) 246-251. 

A diverse range of glycan forms may be produced in some recombinant proteins. For example, the HIV envelope glycoprotein (gpl20) produced from CHO cells contains 24 occupied sequons, of which 13 are complex glycans and 11 are high mannose or hybrid structural forms (Leonard etal., 1990). 

FIGURE 15.1 Three examples of A-linked carbohydrate chains found on glycoproteins oligomannose type (1), A-acetyllactosamine type (or complex type, 2) and hybrid type (3). The common pentasaccharide core is indicated. 

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