Ganglioside composition of rabbit thymus.

Gangliosides of rabbit thymus were extracted and analyzed by the ganglioside-mapping procedure developed previously. 1 g of thymus contained 205.1 nmol of lipid-bound sialic acid and the relative amounts of monosialoganglioside and di- and trisialoganglioside fractions were 76.6 and 23.3%, respectively, as based on lipid-bound sialic acid. No ganglioside containing N-acetylgalactosamine was detected in rabbit thymus. The predominant component was N-glycoloylneuraminosyl lacto-N-norhexaosyl ceramide, NeuGc(alpha, 2-3)Gal(beta, 1-4)GlcNAc(beta, 1-3)Gal(beta, 1-4)GlcNAc(beta, 1-3)Gal(beta, 1-4)Glc(beta, 1-1) ceramide, which constituted 38.4% of the total gangliosides. The other major gangliosides were N-glycoloylneuraminosyl lacto-N-neotetraosyl ceramide (31.3%), GD3 containing N-glycoloylneuraminic acid (11.8%), GM3 containing N-glycoloylneuraminic acid (10.6%) and GM3 containing N-acetylneuraminic acid (6.4%). C-18 sphingosine was the only long-chain base in all the gangliosides. Palmitic acid was the major fatty acid of thymus gangliosides and chromatographically more polar gangliosides contained higher proportions of palmitic acid: 46.3% in GM3, 47.5% in GD3, 60.2% in N-glycoloylneuraminosyl lacto-N-neotetraosyl ceramide and 89.6% in N-glycoloylneuraminosyl lacto-N-norhexaosyl ceramide.