Structure of the phosphosaccharide-inositol core of the Leishmania donovani lipophosphoglycan

The phosphosaccharide-inositol core of the lipophosphoglycan of Leishmania donovani was generated by treatment of the glycoconjugate with mild acid and digestion with phosphatidylinositol-specific phospholipase C. The core was purified and examined by one- and two-dimensional 1H-1H NMR and by methylation analysis. From the results, the carbohydrate core was elucidated as a phosphosaccharide attached to the inositol residue of the lyso-alkylphosphatidylinositol anchor of lipophosphoglycan as follows: PO4----6GalP(alpha 1----6)GalP(alpha 1----3)Galf(alpha 1----3)ManP(alpha 1----3)ManP(alpha 1----4)GlcNP(alpha 1----6)myo-inositol. The presence of an internal galactofuranose residue is highly unusual and the ManP(alpha 1----4)GlcNP(alpha 1----6)myo-inositol sequence is homologous to the respective portion of the glycosylphosphatidylinositol anchors reported for both the Trypanosoma brucei variant surface glycoprotein and the rat brain Thy-1 glycoprotein.