Mass spectrometric analysis of permethylated glycosphingolipids I. Sequence analysis of two blood-group B active glycosphingolipids from human B erythrocyte membranes.

Two blood group B active glycosphingolipids (B-I and B-II) formerly isolated and purified from human B erythrocytes (16) were investigated by mass spectrometry after permethylation. B-I yielded fragments up to m/e 1266 and B-II up to m/e 1495, showing the sequence of six and seven carbohydrate residues respectively. In combination with additional experimental evidence (18) the glycosphingolipids are demonstrated to be a gal- fuc ]-gal-glcNAc-gal-glc-ceramide (B-I) and a gal- fuc ]-gal-glcNAc-gal-glcNAc-gal-glc-ceramide (B-II). Mass spectrometric evidence for the ceramide residues are also obtained indicating besides spingosine C24-,C24:1-, and C22-fatty acids as main constituents.