An extracellular phosphoglycan (exPG), present in the culture medium of the promastigote form of Leishmania donovani, was purified and structurally characterized. The purification scheme included ethanol precipitation of the culture medium, anion exchange chromatography, hydrophobic chromatography on phenyl-Sepharose, and preparative polyacrylamide gel electrophoresis. Structural analysis by 1H-1H NMR, methylation linkage analysis, and glycosidase digestion revealed that the exPG consisted of the following structure: (CAP)?[PO4 -6Galpß1-4Manpa1] 10-11-PO4 -6Galpß1-4Man. The cap was found to be one of several small, neutral oligosaccharides, the most abundant of which was the trisaccharide Galpß1-4(Manpa1-2)Man. The results indicated structural analogy to the cellular-derived lipophosphoglycan (LPG) from L. donovani. The important exceptions are a lack of the lipid anchor, the entire phosphosaccharide core, and several of the repeating disaccharide units. Although the function of exPG is presently unknown, it may play a protective role for the promastigote in the insect vector or during infection of a mammalian host.
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|Publication status||Published - 25 Mar 1992|