BIOCHEMISTRY OF SPHINGOLIPIDS .18. COMPLETE STRUCTURE OF TETRASACCHARIDE PHYTOGLYCOLIPID

The tetrasaccharide (2-mannosido-6-[D-glucosamido-(1-4)-D-glucuronido]inositol) obtained from the hydrolysis of phytoglycolipid has been oxidized with periodate and the products reduced with sodium borohydride. Isolation of o-arabitol as one of the polyol products shows that in the tetrasaccharide the inositol is 2,6-disubstituted. Proton magnetic resonance studies on the derived glucosylinositol and carboxyl-reduced N-acetyl trisaccharide showed that the glucuronic acid moiety was attached to the 6 position of inositol. The mannose, therefore, must be attached to the 2 position of inositol. Also deduced from proton magnetic resonance spectra was the all-α configuration of the tetrasaccharide. Confirmation of this came from the time, of half-hydrolysis of the N-acetyl trisaccharide. The point of attachment of the phosphate to the inositol in phytoglycolipid was shown to be through the 1 position by oxidation studies on the intact phytoglycolipid. The latter point was substantiated by mild acid hydrolysis of phosphorylated oligosaccharide to afford only inositol 1-phosphate. © 1969, American Chemical Society. All rights reserved.