CHARACTERIZATION OF PHOSPHOINOSITOL OLIGOSACCHARIDES FROM PARASITIC PROTOZOA BY FAST-ATOM-BOMBARDMENT AND COLLISIONAL ACTIVATION MASS-SPECTROMETRY

Fast atom bombardment mass spectrometry (FAB MS) enables the rapid, ac curate and sensitive determination of the molecular masses of glycosyl phosphatidylinositol (GPI)-derived oligosaccharides, from which the co mposition in terms of monosaccharide residues and non-carbohydrate sub stituents can be determined. Interpretation of fragment ions in collis ional activation mass spectra further enables the determination of res idue sequence, the positions of branch points, and the location of non -carbohydrate substituents. We have applied these techniques to the ch aracterization of phosphoinositol oligosaccharides from Leptomonas sam ueli, Endotrypanum schaudinni and Leishmania adleri. The mass spectral data permit the postulation of candidate structures for the oligosacc harides, which provide a set of constraints that can assist the interp retation of results from other techniques such as NMR.