Analytical Sciences

Identifying Specific and Differentially Linked Glycosyl Residues in Mammalian Glycans by Targeted LC-MS Analysis

Yi-Li HUANG,* Bing-Yi JHOU,* Sung-Fang CHEN,* and Kay-Hooi KHOO**

*Department of Chemistry, National Taiwan Normal University, 116-77, Taipei, Taiwan
**Institute of Biological Chemistry, Academia Sinica, 115-29, Taipei, Taiwan

Glycans, which are widespread in nature, consist of a large number of monosaccharides linked via glycosidic bonds. Due to the complex nature of glycan structures on glycoproteins, assessing the configuration and positions of the glycosidic linkages of a glycan is a subject of considerable interest. In this study, a method for accomplishing this using partially O-methylated alditols (PMAs) from glycans combined with LC-MS analysis is reported. N-Glycans were first per-methylated with methyl iodide, and the levels of methylation were further confirmed by MALDI-TOF. PMAs were then produced via complete hydrolysis and reduction. PMAs derived from Fetuin N-glycan and Lewis^a antigen carbohydrates were successfully detected by LC-MS analysis. This analysis can be performed without the need for an additional derivatization step for GC analysis, and should be suitable for use in conjunction with a LC-MS-based analysis platform.

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