Monosaccharide composition of glycans based on Q-HSQC NMR

• A method to determine the monosaccharide composition based on NMR was developed.
• Q-HSQC depends of a JCH value of 155 Hz for C-1, allowing milli-microM detection.
• Analysis of the native and hydrolyzed glycan give insights of the molecular mobility.

Glycans have essential functions related to structural architecture and specific cell surface phenomena, such as differentiation, biosignalling, recognition and cell–cell interaction, with the carbohydrate structure determining main function in the cell. Due to the importance of the primary structure, the monosaccharide composition is crucial to show the glycan structure. We now present a method for complex carbohydrates based on NMR spectroscopy, which has shown to give similar results to those obtained by the classic GC–MS-carboxy-reduction/deuterium labeling approach. Quantitative HSQC, through JCH dependence showed 155 Hz as the best value for 1H/13C anomeric aldoses, allowing milli-microM detection using conventional inverse probe heads. Combining the quantification of native monosaccharide units of the glycan and those from the hydrolyzed product, a strong correlation occurs between the molecular mobility of the monosaccharide units, giving rise to some insights on the dynamic properties of the parent glycan.