Automatically Full Glycan Structural Determination with Logically Derived Sequence Tandem Mass Spectrometry

Here we show the full structures of glycans, including diastereomers and anomericity of each monosaccharide and linkage position of each glycosidic bond, can be determined using tandem mass spectrometry guided by a logically derived sequence (LODES). This new method provides de novo oligosaccharide structural identifications with high sensitivity and was applied to automatically in situ structural determination of the oligosaccharides eluted by high performance liquid chromatography. We showed that the structure of a given trisaccharide from trisaccharide mixture and bovine milk were determined from near three thousand isomers by using six to seven logically selected CID spectra. The entire procedure of mass spectrum measurement guided by LODES can be programmed in computer for automatically full glycan structural identification, a goal that remains a great challenge in glycan analysis.