Structure of the major carbohydrate fragment of the Leishmania donovani lipophosphoglycan

The major carbohydrate fragment from the lipophosphoglycan of Leishmania donovani was generated by mild acid hydrolysis (0.02 N HCl, 5 min, 100 degrees C) and purified by chromatography on DE-52 cellulose and thin layer. By a combination of analyses including gas-liquid chromatography-mass spectrometry and 1H NMR, the structure of the fragment was elucidated as PO4----6Gal(beta 1----4)Man. Approximately 16 of these phosphorylated disaccharide units occur in the overall glycoconjugate structure. NMR analysis of an alkaline phosphatase treated phosphorylated tetrasaccharide generated from lipophosphoglycan showed that the phosphorylated disaccharide units are linked together via alpha-glycosidic linkages. Complete characterization of the phosphorylated disaccharide units of lipophosphoglycan provides the first example of a defined carbohydrate anchored in membranes by a derivative of phosphatidylinositol.