On the structure of cytolipin R, a ceramide tetrahexoside hapten from rat lymphosarcoma
Cytolipin R, a ceramide tetrahexoside isolated from rat lymphosarcoma, was studied by sequential hydrolysis with specific glycosidases which revealed the anomeric configurations of the glycosidic bonds. Sugar linkages were established by combined gas liquid chromatography and mass spectrometry of the partially methylated alditol acetates prepared after permethylation and hydrolysis of the intact lipid. Results indicated the structure of cytolipin R to be N acetylgalactosaminyl (β1→3) galactosyl (α1→3) galactosyl (β1→4) glucosyl ceramide. Cytolipin K (globoside I) differs in having a galactosyl (α1→4) galactosyl internal linkage, and this difference must account for the immunological differences between cytolipin K and cytolipin R.