On the structure of two new gangliosides from beef brain

Two new gangliosides were isolated in pure form from beef brain. They were provisionally named ganglioside G5a and G5b. Ganglioside G5a is a monosialoganglioside containing fucose. Its basic neutral glycosphingolipid core is the gangliotetraose ceramide: Gal (1→3) GalNac (1→4) Gal (1→4) Glc (1→) ceramide, most likely with β linkages. Fucose is linked to the 2 position of external galactose, N acetylneuraminic acid to the 3 position of internal galactose. Ganglioside G5b is a mixture of at least two isomeric disialogangliosides containing N acetylneuraminic acid and N glycolylneuraminic acid. The major isomer has the following structure: NeuNac (α,2→3) Gal (β,1→3) GalNac (β,1→4)(NeuNglα,2→3) gal (β,1→4) Glc (β,1→) ceramide. The minor isomer contains N acetylneuraminic acid and N glycolylneuraminic acid in an inverted linkage position.