文摘
We previously reported sequence determination of neutraloligosaccharides by negative ion electrospray tandemmass spectrometry on a quadrupole-orthogonal time-of-flight instrument with high sensitivity and without theneed of derivatization. In the present report, we extendour strategies to sialylated oligosaccharides for analysisof chain and blood group types together with branchingpatterns. A main feature in the negative ion mass spectrometry approach is the unique double glycosidic cleavage induced by 3-glycosidic substitution, producing characteristic D-type fragments which can be used to distinguish the type 1 and type 2 chains, the blood grouprelated Lewis determinants, 3,6-disubstituted core branching patterns, and to assign the structural details of eachof the branches. Twenty mono- and disialylated linear andbranched oligosaccharides were used for the investigation,and the sensitivity achieved is in the femtomole range.To demonstrate the efficacy of the strategy, we havedetermined a novel complex disialylated and monofucosylated tridecasaccharide that is based on the lacto-N-decaose core. The structure and sequence assignment wascorroborated by methylation analysis and 1H NMR spectroscopy.
