Structures of Glycolipids

The 0-linked oligosaccharides of L-serine and L-threonine are alkali labile. When treated with alkali, these 0-linked oligosaccharides are released by a P-elimination reaction to form unsaturated amino acids and the free sugar chain (see Fig. 9.2B,C and section 12.11 in Chapter 12). 5-Linked oligosaccharides to L-cysteine are also released by an identical reaction (see Fig. 9.2F). 0-linked oligosaccharides to hydroxy-L-lysine, hydroxy-L-proline, or phenolic hydroxyl of L-tyrosine are not readily released by alkali. 

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The mesogenic structures of glycolipids are due to the occurrence, on the same molecule, of a hydrophilic and a hydrophobic moiety often referred to as head and tail respectively. As a result, glycolipids are able to self-organize into a large variety of mesophases also called liquid crystals (Fig. 2) [ 10]. Supramolecular assemblies of mesogenic compounds can be caused by a rise in temperature (thermotropic liquid crystals) or by the addition of water (lyotropic liquid crystals) they result from different responses of the carbohydrate and the alkyl chain to temperature or solvent (water), respectively. 

Fujino, Y., Nakano, M. and Saeki, T. 1970. The chemical structure of glycolipids of bovine milk. Agr. Biol. Chem. (Japan) 34, 442-447. 

The L2/HNK-1 epitope is a sulfated glucuronic-acid-containing oligosaccharide structure of glycolipids [63], As indicated by the reactivity with the L2 monoclonal antibody,... 

FAB mass spectrometry is a powerful tool for analyzing the structure of glycolipids. Especially in combination with a linked scan at constant B/E, it provides unambiguous information on the fatty acid composition, the location of double bonds in the long-chain base (Ci9-sphingadienine), or the presence of phosphodihexose. 

A considerable amount of information regarding the glycan structures of glycolipids may be obtained by a combination of methylation and mass spectral analysis of the intact molecule. Sialic acids are easily removed, and oligosaccharide chains may be cleaved from the lipid portion either chemically or enzymatically with a specific endo-glycoceramidase. 

Fig. 6. Membrane iipids. Basic structures of glycolipids and their subclasses, the glyceroglycolipids and the sphingoglycolipids. R = rest of the glycosidic polar moiety. R R" = hydrocarbon chains. Y = nonpolar residue.

Fig. 18 Molecular structures of glycolipids 103-107 and representation of their liposome formation...

Bergter and Vermelho, 2010. Structures of Glycolipids Found in Trypanosomatids Contribution to Parasite Fimctions, The Open Parasitology Journal, 2010, 4 84-97. 

Hakomori, S., Gahmberg, C. G., and Laine, R. A., 1974, Growth behavior of transformed cells as related to the surface structures of glycolipids and glycoproteins, in Sixth Annual Miami Winter Symposia, Dept, of Biochem., Univ. of Miami, pp. 49-52. 

Figure 5. The structures of glycolipids synthesized in this study...

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