Separation of phosphorylated sugars using capillary electrophoresis with indirect photometric detection

Adenosine monophosphate (AMP) and naphthalene disulfonate (NDS) have been characterized as electrolytes for the indirect photometric detection of phosphorylated sugars and other organophosphorus compounds of biochemical interest. This work has resulted in the CE separation on an uncoated capillary using 5 mM AMP and 100 mM boric acid at pH 7.2 of six metabolites (glucose-6-phosphate [G6P], fructose-6-phosphate [F6P]), fructose-1,6-bisphosphate [F-1,6-P], dihydroxyacetone phosphate [DHAP], glyceraldehyde-3-phosphate [G3P], and 2-phosphoglycerate [2-PG] or 3-phosphoglycerate [3-PG]) found in the glycolytic pathway. The detection limits using a 5-sec injection time were between 0.5 and 1 mg/L for these compounds, with the exception of G3P. Resolution between 3-PG and 2-PG is possible by the addition of magnesium ion, although the separation time is longer. A successful separation of five monophosphorylated sugars (G6P, F6P, ribose-5-phosphate [R5P], sucrose-6-phosphate [S6P], and 2-PG) has been performed using the same conditions as for the glycolytic pathway separation. A separation of bisphosphorylated sugars (glucose-1,6-bisphosphate [G-1,6-P],F-1,6-P, ribulose-1,5-bisphosphate [Ru-1, 5P], and sedoheptulose-1,7-bisphosphate [S-1, 7P]) could not be performed with AMP unless magnesium chloride was added. With NDS, a separation of these bisphosphorylated sugars can be obtained without the addition of magnesium chloride.