Differentiation of stereochemistry of glycosidic bond configuration: Tandem mass spectrometry of diastereomeric cobalt-glucosyl-glucose disaccharide complexes

Configurations of glycosidic linkages (alpha or beta) in a series of 1,3-, 1,4-, and 1,6-glucosyl-glucose disaccharides were differentiated by tandem mass spectrometry. Diastereomeric octahedral complexes, [Co+3(acac)(2)/disaccharide](+), were generated in situ via fast-atom bombardment ionization. Mass-analyzed, ion kinetic energy spectra of the metastable complexes obtained in the absence of collision gas indicated that the major product ion results from the loss of an acetylacetonate Ligand, which thus generates the ion [Co+2(acac)/disaccharide](+). Kinetic energy release measurements for this dissociation display a consistently greater value for complexes that possess an alpha-linked disaccharide relative to those that possess beta-Linked disaccharides, regardless of linkage position.