Strategies for the structure determination of parasite glycoconjugates using fast atom bombardment mass spectrometry

RESUMO

Fast atom bombardment mass spectrometry (FAB MS) is a sensitive and powerful technique for the analysis of thermally labile and involatile materials. In this paper we describe the application of the method to the characterization of oligosaccharides isolated from the cell surface glycoconjugates of parasitic protozoa. The spectra typically contain both molecular ions, which define the monosaccharide composition, and fragment ions which are related to the structure of the intact molecules. The use of additional techniques such as chemical derivatization and colisional activation enhances fragmentation and simplifies interpretation of the data, enabling the determination of residue sequence, the positions of branch points, and the location of noncarbohydrate substituents. We have applied these techniques to the characterization of phosphoinositol oligosaccharides from members of the Trypanosoma family, including Leptomonas smueli, Endotrypanum schaudinni and Leishmania adleri. Although it is not usually possible to determine the complete structure of oligosaccharide by mass spectrometric methods alone, the information gained greatly simplifies the interpretation of the results from other techiniques such as nuclear magnetic resonance and methylation analysis.