Effect of monosaccharide composition, glycosidic linkage position and anomericity on the electrophoretic mobility of labeled oligosaccharides

Fluorophore-assisted carbohydrate electrophoresis (FACE) is useful for separation and characterization of oligosaccharides from various sources and for comparing several samples at once. While characterizing fungal surface glycans by FACE we observed that samples and standards of the same mass did not comigrate as expected. Subsequent experiments showed that the samples did not contain contaminating sugars. Therefore, our observation suggested that glycan electrophoretic mobility is affected by factors in addition to molecular mass. This work assesses the contribution of monosaccharide composition, linkage position, and linkage anomericity to glycan mobility. Commercially available (and synthesized when available) bioses of known composition were derivatized with a charged fluorophore, and electrophoretic mobilities compared in a slab gel format. The results indicate that all three parameters mentioned above affect observed migration. Further, no migration patterns emerged to suggest a set of rules for assigning band identity based on mobility alone. These results emphasize the importance of including known, matched, standards to facilitate interpretation of FACE data.