Purification of Fc-fusion proteins without Chromatography, polymers, membranes or specific ligands

We introduce a new concept and a potentially general platform for the purification of Fc- fusion proteins that does not rely on any resins, chromatographic media, membranes or specific ligands but, rather, makes use of aromatic [metal–chelator] complexes. We modified and significantly expanded our existing technology which was used to purify antibodies in our previous studies. Our fully aromatic complex is composed of the chelator bathophenanthroline (batho) and metal ions (zinc or copper ions) to form [(batho)3:Zn2+] or [(batho)3:Cu2+] complexes. Our technology captures the target proteins quantitatively via [cation–pi] and [pi–pi] interactions and allows for their recovery at high yields (>80%, by densitometry) and purity (≥90%, by SDS-PAGE) while preserving their secondary structure, enzymatic activity and monomeric state. The entire process is performed at pH 7, thereby avoiding the complications that derive from exposure to harsh acidic conditions (e.g., aggregation or partial denaturation). The monomeric dispersity was preserved after the elution and evaluated by DLS (dynamic light scattering) and native page gel electrophoresis. The secondary structure of the target protein was not affected during the purification process and was confirmed by the technique of CD (Circular Dichroism). The biological activity of the purified protein was assessed and was preserved. Its cost-effectiveness and simple integration into the future industrial-scale downstream processing of therapeutic-grade biopharmaceuticals will be discussed. In future, we are planning to apply the same purification technology to different types of therapeutic proteins as an efficient purification platform while applying the necessary modifications.