High resolution slab gel electrophoresis of 8-amino-1,3,6-pyrenetrisulfonic acid (APTS) tagged oligosaccharides using a DNA sequencer

A novel electrophoretic method for the analysis of oligosaccharides using DNA sequencer technology is illustrated using malto-oligosaccharide distributions obtained following isoamylase digestion of glycogen, wheat starch and potato starch. The debranched starches were derivatized at the reducing end with the charged fluorophore 8-amino-1,3,6-pyrenetrisulfonic acid (APTS). This highly reproducible method provides baseline resolution of oligomers from chain lengths of 3 to more than 80 glucose units, and exhibits high sensitivity with detection thresholds of one femtomole per resolved band. In addition, the reductive amination procedure attaches a single fluorophore per oligosaccharide, allowing calculation of the results on either a mass or a molar basis. The efficacy of the method is illustrated through the determination of the profile of individual oligosaccharides of chain length with a degree of polymerization (DP) < 80, derived from loading less than 15 ng per analysis of glycogen, wheat and potato starches. While the results obtained were superior in resolution and sensitivity to previously reported observations using a range of techniques, they were nonetheless consistent with the overall differences between these polysaccharides. The resolution, sensitivity, reproducibility and high throughput of the method provides substantial advantages over existing methods for the analysis of linear oligosaccharide chain length distributions.