Sphingosine glycolipid structure

Glycolipid Structure containing one or more saccharide units covalently attached to the primary hydroxyl group of iV-acyl sphingosine (ceramide), a C-18 amino alcohol. Those containing sialic acid are termed ganglio-sides. 

The lipids described in sections 6.2.2 and 6.2.3 were based on a glycerol backbone. However, another important group of acyl lipids have sphingosine-based structures. Both glycolipids and phospholipids are found, with some compounds capable of dual classification, i.e. phospholipids which contain sugar residues. 

Measurements of the quantities of glycolipids inserted into the membrane have also been reported by a technique based on the use of C-labeled lipid anchors. In this method, the carbohydrate (a-o-Man) was covalently coupled to the anchor at the surface of a pre-formed vesicle. Indeed, the liposome structure was shown to remain intact in the treatment. Nevertheless, the measurement of the incorporated mannose was performed after separation of bound and unbound material by centrifugation. The yields of coupling were shown to increase with the increase of the initial mannose/ C-anchor ratio, but non covalent insertions were displayed at high initial mannose concentrations. Therefore, the aforementioned method was not as accurate as could have been expected for the use of radioactive materials [142]. Radiolabeled phospholipids were also used for such determinations thus the amounts of glycosphingolipids incorporated into liposomes were quantified by the use of H-phospholipids whereas the amounts of glycolipids were determined by a sphingosine assay [143]. 

From the sponge M. incrustans, two cerebrosides and a polar glycolipid were isolated.78 Both cerebrosides contain galactose and sphingosine, but differ in the nature of their fatty acids the less polar cerebroside contains normal, and the more polar, monohydroxy, acids. The structure of the polar glycolipid was not established, but it was shown to contain sphingosine, fatty acids, galactose, arabinose, fucose, and phosphorus.78... 

Glycosphingolipids, or glycolipids, include the cerebrosides, sulfatides, and gan-gliosides and are built on a ceramide backbone structure, which is a fatty acid amide derivative of sphingosine ... 

Fig. 33.5. General structures of the sphin-golipids. The backbone is sphingosine rather than glycerol. Ceramide is sphingosine with a fatty acid joined to its amino group by an amide linkage. Sphingomyelin contains phos-phocholine, whereas glycolipids contain carbohydrate groups.

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