Isolation and characterization of four major neutral glycosphingolipids from the liver of the English sole (Parophrys vetulus). Presence of a novel branched lacto-ganglio-iso-globo hybrid structure.

We have previously reported on carbohydrate structures of the major acidic glycosphingolipids from the liver of the English sole, Parophrys vetulus (Ostrander, G. K., Levery, S. B., Hakomori, S., and Holmes, E. H. (1988) J. Biol. Chem. 263, 3103-3110). We have now isolated four major neutral glycosphingolipids from English sole liver. They have been characterized by 1H nuclear magnetic resonance spectroscopy, methylation analysis, and by fast atom bombardment-mass spectrometry. In addition to neutral glycosphingolipids with known structures (CMH, lactosylceramide, and Gg3), a major polar neutral glycosphingolipid was isolated and characterized as having the following novel structure: (formula; see text) The compound represents a novel hybrid of neolacto-, ganglio-, and iso-globo-series glycosphingolipid structures, a combination not previously encountered. Furthermore, the linkage Fuc alpha 1----3GalNac has not been previously reported for a glycosphingolipid. The relationship of these structural elements to known glycoconjugates is discussed.