Theoretical study of deprotonated glucopyranosyl disaccharide fragmentation

Molecular orbital calculations were used to investigate the fragmentation of deprotonated glucopyranosyl disaccharides. Based on data from collisional activation and isotopic labeling experiments, fragmentation mechanisms are proposed, with calculated transition states being used to study the energetics of fragmentation. The calculations suggest that deprotonation at the C(2) hydroxyl of the non-reducing ring, following ring opening, may be important for disaccharide fragmentation. It is also shown that the stereochemistry at the 2-position of the non-reducing ring may have a significant effect on disaccharide fragmentation, particularly with regard to determination of the anomeric configuration.