Capillary electrophoresis of sialic acid-containing glycoprotein. Effect of the heterogeneity of carbohydrate chains on glycoform separation using analpha(1)-acid glycoprotein as a model

alpha (1)-Acid glycoprotein (AGP) showed multiple peaks on separation using capillary electrophoresis in a chemically modified capillary dth dimethylp olysiloxane at slightly acidic conditions. We analyzed glycoforms of AGP sp ecies after separation by ion-exchange chromatography Con A affinity chroma tography, and Cu(II)-chelating affinity chromatography. The AGP species thu s obtained were digested with N-glycosidase F, and the released carbohydrat e chains were analyzed by high-performance liquid chromatography after labe ling with 3-aminobenzoic acid. The results afforded basic information on th e contribution of carbohydrate chains to the separation mechanism of glycof orms of AGP by capillary electrophoresis, In addition, we describe an easy method for AGP analysis in serum samples using the electrokinetic injection .