Theoretical study of deprotonated glucopyranosyl disaccharide fragmentation

Molecular orbital calculations were used to investigate the fragmentation o f 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 energe tics of fragmentation. The calculations suggest that deprotonation at the C (2) hydroxyl of the non-reducing ring, following ring opening, may be impor tant for disaccharide fragmentation. It Is also shown that the stereochemis try at the 2-position of the non-reducing ring may have a significant effec t on disaccharide fragmentation, particularly with regard to determination of the anomeric configuration. Copyright (C) 1999 John Wiley & Sons, Ltd.