New methods of protein purification: Affinity ultrafiltration

This review describes a recently developed method for protein purification-affinity ultrafiltration. In affinity ultrafiltration, the protein to be purified is complexed with a macroligand composed of a soluble polymer or an insoluble microparticle with covalently bound, target protein-specific affinity ligands. The complex is trapped by an ultrafiltration membrane, whereas unwanted proteins pass through the membrane. The unwanted proteins are removed from the system by the carrier liquid. The system is then supplemented with an agent eluting the target protein by dissociating it from the microligand complex. The purified protein then passes the membrane, while the macroligand is trapped by it. The macroligand can be re-used after regeneration. Affinity ultrafiltration has a number of advantages over other protein purification techniques: 1) commercial availability of ultrafiltration systems with various high-productivity designs; 2) availability of presynthesized macroligands, which can be supplemented with additional, easily manufactured, commercial latex-based macroligands; 3) rapid separation of large solution volumes; 4) repeated use of equipment, enabling consecutive purification of different proteins; 5) simple scale-up and automation procedures.