Antibody Purification: Ion-Exchange Chromatography

Ion exchange chromatography techniques are the focus of this chapter and they showcase the power of this method for the purification of proteins and monoclonal antibodies. The technique is powerful and can separate biomolecules that have minor differences in their net charge, e.g., two protein molecules differing by a single charged amino acid. Given the amphoteric character of proteins the pH of the solution is important in the determination of the type of ion exchanger used. Immunoglobulins, although they can be purified by either cation or anion exchange chromatography, are most frequently purified by anion exchange with DEAE resins. The purification of the rabbit IgG fraction from serum using a DEAE column is detailed as well as the purification of IgG from ascitic fluid using FPLC, from loading to elution of the purified and concentrated protein.