A NOVEL DIFUCOSYLATED NEUTRAL GLYCOSPHINGOLIPID FROM THE EGGS OF THE SEA-URCHIN, HEMICENTROTUS-PULCHERRIMUS .1. PURIFICATION AND STRUCTURAL DETERMINATION OF THE GLYCOLIPID

A novel fucose-containing neutral glycosphingolipid (GL-5) was purified from the eggs of the sea urchin, Hemicentrotus pulcherrimus. The chemical structure was determined to be Fuc-alpha-1-3GalNAc-beta-1-4(Fuc-alpha-1-3)GlcNAc-beta-1-4Glc-beta-1-1Cer by methylation analysis, partial acid hydrolysis, fast atom bombardment mass spectrometry, and proton nuclear magnetic resonance spectroscopy. The unique characteristics of GL-5 are that: the reducing terminal disaccharide portion is not Gal-beta-1-4Glc but GlcNAc-beta-1-4Glc; it includes a GalNAc-beta-1-4GlcNAc sequence and a Fuc-GalNAc linkage; the defucosylated core is a novel trisaccharide chain; and the sugar structure is one of the smallest ever characterized for a difucosylated glycolipid. The major fatty acids were 22:1 and 22h:1, and about 30% of the total acids was 2-hydroxylated. All the long-chain bases were phytosphingosines, of which about 90% was n-t18:0. The similarity of the ceramide moiety to that of glucosylceramide from the same eggs [Kubo, H. et al. (1992) J. Biochem. 111, 726-731] suggests a close biosynthetic relationship between GL-5 and the glucosylceramide.