Effects of electrolyte modification and capillary coating on separation ofglycoprotein isoforms by capillary electrophoresis

The capillary electrophoresis (CE) running electrolyte composition was opti mized for the separation of selected glycoproteins. A good separation of th e ovalbumin (OV) and alpha -acid glycoprotein (AAG) isoforms was achieved i n 20 mmol.L-1 N-(2-hydroxyethyl)piperazine-2'-(2-ethanesulfonic acid) (HEPE S) at pH 7.0, in 20 mmol.L-1 phosphate, pH 7.0, or in 25 mmol.L-1 berate, p H 7.9. Various ways of suppression of the glycoprotein adsorption onto the capillary wall were compared. alpha, omega -Diamine alkanes and bis(aminoal kyl) amines were added to the CE buffers, the optimized concentration being 1 mmol.L-1 in 20 mmol.L-1 phosphate buffer. The OV and AAG isoforms could be separated using all the alpha, omega -diamine alkanes or bis(2-aminoethy l)amine. The length of the alkyl chain in the diaminoalkane did not influen ce the separation. The separation of the isoforms of pollen allergens was a lso tested. The effects of modification of the capillary wall by succinyl-p oly-L-lysine and hydrophilic CElect-P1 capillary were compared. A decrease in the glycoprotein and protein adsorption resulted in an improved separati on of the isoforms.