Characterization of a novel ceramide octasaccharide isolated from whole tissue of a fresh-water bivalve, Corbicula sandai.

A novel glycosphingolipid containing two mannose residues, provisionally named GL-1 in a previous paper (Itasaka, O. and Hori, T. (1979) J. Biochem. 85, 1469-1481), was isolated from whole tissue of a fresh-water bivalve, Corbicula sandai, and the structure of the glycolipid was determined to be: Galp4Me(beta1 more than 3)GalpNAc(beta1 more than 3)Fucp(alpha1 more than 4)GlcpNAc(beta1 more than 2)Manp(alpha1 more than 3)(Xylp(alpha1 more than 2))Manp(beta1 more than 4)Glcp(beta1 more than 1)Cer. Glycosphingolipid-1 seems to be a biosynthetic precursor of glycosphingolipid-3, because they have an identical octasaccharide structure, except for the presence of an aminoethylphosphoryl residue in glycospingolipid-3. However, in contrast to glycosphinogolipid-3, glycosphingolipid-1 has a more complex ceramide pattern. This fact suggests that glycosphingolipid-1 as isolated is not a degradation product of glycosphingolipid-3, and it can be presumed that the restricted molecular species of glycosphingolipid-1 which has the same ceramide constitution as glycosphingolipid-3 may be utilized preferentially for glycosphingolipid-3 biosynthesis.