Protein binder for affinity purification of human immunoglobulin antibodies.

The importance of a downstream process for the purification of immunoglobulin antibodies is increasing with the growing application of monoclonal antibodies in many different areas. Although protein A is most commonly used for the affinity purification of antibodies, certain properties could be further improved: higher stability in alkaline solution and milder elution condition. Herein, we present the development of Fc-specific repebody by modular engineering approach and its potential as an affinity ligand for purification of human immunoglobulin antibodies. We previously developed the repebody scaffold composed of Leucine-rich repeat (LRR) modules. The scaffold was shown to be highly stable over a wide range of pH and temperature, exhibiting a modular architecture. We first selected a repebody that binds the Fc fragment of human immunoglobulin G (IgG) through a phage display and increased its binding affinity up to 1.9 × 10–7 M in a module-by-module approach. The utility of the Fc-specific repebody was ...