DIFFERENTIATION OF CA2-COORDINATED AND MG2+-COORDINATED BRANCHED TRISACCHARIDE ISOMERS - AN ELECTROSPRAY-IONIZATION AND TANDEM MASS-SPECTROMETRY STUDY()

Three isomeric branched trisaccharides coordinated to calcium and magn esium were analyzed by electrospray ionization followed by tandem mass spectrometry. Studies were undertaken to optimize the singly charged metal coordinated precursor prior to MS/MS and MS/MS/MS experiments. T he positioning of the glycosidic linkages between reducing and nonredu cing rings could be determined in all three isomers, and the linkage o f the fucose ring was obvious in two of the three isomers when calcium was used as the coordinating metal. The ionic radius and charge of th e metal appear to be very important in obtaining structural informatio n in these isomers.