Protein A has been a fantastic tool for the antibody industry. It is without doubt the most well-established purification technique in monoclonal antibody (MAb) manufacturing today due to a few key success factors. Protein A is the result of the long evolution of Staphylococcus aureus that developed a defense system against antibodies. Protein A exists on the cell wall of about 9% of S. aureus strains and immobilizes IgGs. When there is an immune response in the body, the bacterium defends itself by disabling IgG molecules, preventing them from attacking the cells. With this natural origin, it is hard to engineer an alternative with superior selectivity.
Despite protein A’s natural origins, the bioindustry has worked to make it more useful in industrial manufacturing by improving its alkaline stability. We have even played with the structure of protein A to increase the amount of binding domains. Throughout the generations of protein A resins, this engineering has made protein A a more effective tool at lower production costs.
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Jonathan Royce is Global Business Leader for Chromatography Resins at GE Healthcare Life Sciences.