LOSS OF INTERNAL 1-]6-SUBSTITUTED MONOSACCHARIDE RESIDUES FROM UNDERIVATIZED AND PER-O-METHYLATED TRISACCHARIDES

The fragmentation behavior of [M + H](+) ions of a series of underivat ized and per-O-methylated trisaccharides having 1 --> 6 linked residue s, of which one or two is a deoxy-fluoro or deoxy residue and thus has a unique mass, has been studied by using collision-induced dissociati on fast-atom bombardment mass spectrometry. In addition to the usual f ragment ions resulting from glycosidic bond cleavage, fragment ions we re observed which must have been generated following an unusual rearra ngement process which can be rationalized in terms of the loss of an i nternal monosaccharide residue. (C) 1997 American Society for Mass Spe ctrometry