Glycolipids of murine lymphocyte subpopulations. Structural characterization of thymus gangliosides

Abstract

Several sialic acid-containing glycolipids have been isolated and purified from murine thymus. Eleven of these acidic glycolipids (gangliosides) have been analyzed by several techniques, permitting us to propose a tentative structure for each. Sugar analysis reveals that all 11 gangliosides contain the same base structure, Gal(beta 1-3)GalNAc(beta 1-4)Gal(beta 1-4)Glc(beta 1-1) ceramide, which is gangliotetraosylceramide. No glucosamine or fucose is present in glycolipids from this tissue. There appears to be considerable heterogeneity in the sialic acid moiety of these gangliosides with respect to their structures and linkages. One ganglioside contains only N-glycolylneuraminic acid. Four of the gangliosides are common brain-type structures and contain sialic acid linked to internal galactose which is insusceptible to Vibrio cholerae neuraminidase. In addition, four of the gangliosides are susceptible to base hydrolysis and are believed to contain O-acetyl derivatives of sialic acid. Two gangliosides have also been shown to contain both N-acetyl- and N-glycolylneuraminic acid. There is also heterogeneity within the ceramide portion of some gangliosides which may be responsible for the appearance of an additional three ganglioside bands on thin layer chromatography.