Structure of the major carbohydrate fragment of the Leishmania donovani lipophosphoglycan. Biochemistry

ABSTRACT: The major carbohydrate fragment from the lipophosphoglycan of Leishmania donovani was generated by mild acid hydrolysis (0.02 N HC1, 5 min, 100 "C) and purified by chromatography on DE-52 cellulose and thin layer. By a combination of analyses including gas-liquid chromatography-mass spec-trometry and 'H NMR, the structure of the fragment was elucidated as P04-6Gal(@l-4)Man. Ap-proximately 16 of these phosphorylated disaccharide units occur in the overall glycoconjugate structure. NMR analysis of an alkaline phosphatase treated phosphorylated tetrasaccharide generated from lipo-phosphoglycan showed that the phosphorylated disaccharide units are linked together via a-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. x e protozoan parasite Leishmania donovani is able to live successfully in two harsh hydrolytic environments in its di-genetic life cycle: as an extracellular promastigote in the alimentary tract of its sandfly vector and as an intracellular amastigote in lysosomes of cells of the reticuloendothelial system of its mammalian host. That L. donovani has adapte