Charge determination of oligosaccharides from human serum EPO.

Determination of charge state for the oligosaccharide structures from human serum EPO and rhEPO was demonstrated by weak anion exchange chromatography based on the method of Guile et al.42Classes of charged N-glycans, named mono-, di-, tri-, and tetra-acidic structures, were assigned by comparison with standard bovine fetuin sugars released and labeled in the same way.43-45 (A) Panels Ai and Aii represent charged 2-AB glycans from human serum EPO from a patient with aplastic anemia before (Ai) and after (Aii) digestion with Arthrobacter ureafacienssialidase. Panel Aiii: 2-AB glycans from another patient with aplastic anemia. Panel Aiv: 2-AB glycans from bovine fetuin (20 pmol). (B) Panel Bi: 2-AB glycans from epoetin alfa (20 pmol). Panel Bii: 2-AB glycans from epoetin beta (20 pmol). Panel Biii: 2-AB glycans from epoetin omega (20 pmol). Panel Biv: 2-AB glycans from bovine fetuin (20 pmol).