Isolation and structural characterization of N-acetyl- and N-glycolylneuraminic-acid-containing GalNAc-G(D1a) isomers, IV(4)GalNAcIV(3)Neu5AcII(3)Neu5GcGgOse(4)Cer and IV(4)GalNAcIV(3)Neu5GcII(3)Neu5AcGgOse(4)Cer, from bovine brain

A ganglioside preparation containing two structurally related minor gangliosides (Gg 1 + 2) was isolated from bovine brain ganglioside mixture and characterized. Treatment of 50 g ganglioside mixture with Clostridium perfrigens sialidase, followed by chromatography on DEAE-Sepharose and silica gel columns, yielded 20 mg Gg 1 + 2. By chemical analysis H-1- and C-13-NMR spectroscopy, enzymic hydrolyses using human beta-hexosaminidase A and clostridial sialidase, and TLC overlay with the conjugated cholera toxin B subunit, the two novel gangliosides Gg 1 and Gg 2 were identified to be: Gg 1, GalNAc-G(Dla)(Neu5Ac/Neu5Gc), beta-GalNac-(1-4)-[alpha-Neu5ac-(2-3)]-beta-Gal-(1-3)-beta-GalNAc-(1-4)-[alpha-Neu5Gc-(2-3)]-beta-Gal-(1-4)-beta-Glc-(1-1)-Cer; Gg 2, GalNac-G(Dla)(Neu5Gc/Neu5Ac), beta-GalNac-(1-4)-[alpha-Neu5Gc-(2-3)]-beta-Gal-(1-3)-beta GalNac-(1-4)-[alpha-Neu5Ac-(2-3)]-beta-Gal-(1-4)-beta-Glc-(1-1)-Cer. The two gangliosides contain the identical pentasaccharide backbone except that the substition of the two sialic acids, Neu5Ac and Neu5Gc, are in the reversed position of the external and the internal Gal residues. Our analyses showed that the content of Gg1 and Gg2 were approximately 0.12% and 0.08%, respectively, of the total brain ganglio-side mixture.