ISOLATION AND STRUCTURAL CHARACTERIZATION OF N-ACETYL-ACID-CONTAININGAND 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 ga ngliosides (Gg 1 + 2) was isolated from bovine brain ganglioside mixtu re and characterized. Treatment of 50 g ganglioside mixture with Clost ridium perfrigens sialidase, followed by chromatography on DEAE-Sephar ose and silica gel columns, yielded 20 mg Gg 1 + 2. By chemical analys is 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 an d Gg 2 were identified to be: Gg 1, GalNAc-G(Dla)(Neu5Ac/Neu5Gc), a-Ne u5Gc-(2-3)]-beta-Gal-(1-4)-beta-Glc-(1-1)-Cer; Gg 2, GalNac-G(Dla)(Neu 5Gc/Neu5Ac), Nac-(1-4)-[alpha-Neu5Gc-(2-3)]-beta-Gal-(1-3)-beta a-Neu5 Ac-(2-3)]-beta-Gal-(1-4)-beta-Glc-(1-1)-Cer. The two gangliosides cont ain the identical pentasaccharide backbone except that the substition of the two sialic acids, Neu5Ac and Neu5Gc, are in the reversed positi on 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%, re spectively, of the total brain ganglio-side mixture.