Ceramide hexoside

Acetyl CoA can be converted to fatty acyl CoA by one of two routes. One utilises 3-hydroxyacyl CoA dehydrogenase and the other, which proceeds via malonyl CoA, uses acetyl CoA carboxylase. The former route is considered to be reversible and 3-hydroxyacyl CoA dehydrogenase is therefore an enzyme of fatty acid oxidation also. When formed, fatty acyl CoA can be incorporated into other lipids as shown in Figure 2.11. Palmityl CoA, however, has other important utilisation routes leading to the synthesis of sphingomyelins (phospholipid) or ceramide hexosides. The latter represent an important junction of lipid and hexose metabolism and are precursors of the gangliosides which contain hexose, hexosamine, and A -acetylneuraminic acid (referred to briefly under glycolipid synthesis above). 

Suzuki, K., and Chen, G. C., 1967, Brain ceramide hexosides in Tay-Sachs disease and generalized gangliosidosis (GMl-gangliosidosis), J. Lipid Res. 8 105-113. 

Kannan and coworkers also used M hydrochloric acid at 100° for the hydrolysis of neutral glycolipids 6 h was found sufficient for hydrolysis of galactolipids, but 12 h was required for complete cleavage of the glucose-ceramide bond. The use of standard ceramide mono- and di-hexosides subjected to hydrolysis for 12 h gave monosaccharide recoveries of >94%... 

Ceramide tri- and tetra-hexosides (having amino sugar residues, as well) were isolated from human organs. These ceramide oligosaccharides proved to be mainly anomalous degradation products of gangliosides (see Section IX, p. 428). 

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