Structure determination of phosphoinositol oligosaccharides from parasitic protozoa using fast atom bombardment mass spectrometry

Glycosylphosphatidylinositols (GPIs) are widely distributed membrane constituents of protozoa and higher eukaryotes, where they anchor proteins and other macromolecules to the cell surface. Free glycosylinositol phospholipids (i.e. not attached to protein or polysaccharide) have also been detected in some parasitic protozoa, and are thought play a role in the interaction of parasite and host. This paper describes the fast atom bombardment mass spectrometry (FABMS) of glycosylinositol phospholipids from the Trypanosomatid parasites Leptomonas samueli, Endotrypanum schaudinni and Leishmania adleri . FABMS in the positive‐and negative‐ion modes in conjunction with collisional activation permits the rapid determination of the monosaccharide composition, the sequence of residues, the branching pattern and the nature and location of non‐carbohydrate substituents. When supplemented by high‐field NMR, FABMS provides a highly efficient route to the complete structure elucidation of these materials.