Neutral glycosphingolipids and gangliosides of bovine thyroid

By the application of a ganglioside-mapping technique, the lipid composition of bovine thyroid was analyzed systematically. The contents of cholesterol, lipid-bound phosphorus and lipid-bound sialic acid in bovine thyroid were 5.10, 9.76, and 0.28 mumol/g of dry tissue, respectively, and the molar ratio of cholesterol, lipid-bound sialic acid, and lipid-bound phosphorus was 52.4 : 2.9 : 100.0. The following phospholipids were contained in this order: phosphatidylcholine greater than phosphatidylethanolamine greater than sphingomyelin greater than phosphatidylserine and phosphatidylinositol greater than cardiolipin. When compared on a molar basis, the amount of total glycosphingolipids was only 3% of phospholipids. As the major neutral glycosphingolipids, ceramide glucoside, ceramide galactoside, ceramide lactoside, ceramide trihexoside and globoside were identified and the most abundant component was globoside (40% of total neutral glycosphingolipids). On the other hand, five molecular species of gangliosides were identified: GM3, GM1, fucosyl GM1, GD3, and GD1a. Three types of GD3 and GD1a with a different sialic acid composition were recognized on the ganglioside-map and isolated in pure forms. GM3 was the most abundant component, but the concentration of gangliosides with ganglio-N-tetraose in bovine thyroid was higher than that of gangliosides with lactose. Also fucosyl GM1 comprised 13% of total gangliosides. Thus, the high concentrations of gangliosides with ganglio-N-tetraose and fucosyl GM1 seemed to be characteristic of bovine thyroid glycosphingolipids. The glycosphingolipids contained in the following order: GM3 greater than GD1a greater than globoside greater than GM1 greater than ceramide trihexoside greater than fucosyl GM1 greater than ceramide lactoside greater than ceramide glycoside greater than GD3 greater than ceramide galactoside.