Studies on glycosphingolipids of fresh-water bivalves. IV. Structure of a branched globoside containing mannose from spermatozoa of the fresh-water bivalve, Hyriopsis schlegelii.

1. A second novel globoside, provisionally named Lipid II in the previous study, was obtained from spermatozoa of the fresh-water bivalve, Hyriopsis schlegelii. The structure of this globoside was established by the results of partial acid hydrolysis, methylation studies, and oxidation with chromium trioxide. 2. The structure was shown to be GlcNAcbeta(1 leads to 2)Manbeta(1 leads to 3)[Xylbeta(1 leads to 2)]Manbeta(1 leads to 4)Glcbeta-(1 leads to 1)-ceramide. It is structurally related to the previously described globoside (Lipid I), except that a branched xylose is linked to the heterooligo saccharide chain of the latter lipid. 3. The predominant fatty acids were palmitic and stearic acids, and octadeca-4-sphingenine was the principal base, amounting to 70% of the total. The fatty acid and long-chain base compositions show nearly the same distribution in both of these globosides.