Affinity chromatography utilizing specific interactions between therapeutic proteins and bead-immobilized capturing agents is a standard method for protein purification, but its scalability is limited by long purification times, activity loss by the capturing molecules and/or purified protein, and high costs. Here, we report a platform for purifying therapeutic antibodies via affinity precipitation using the endogenous calcium ion-binding protein, calsequestrin (CSQ), which undergoes a calcium ion-dependent phase transition. In this method, ZZ-CSQ fusion proteins with CSQ and an affinity protein (Z domain of protein A) capture antibodies and undergo multimerization and subsequent aggregation in response to calcium ions, enabling the antibody to be collected by affinity precipitation. After robustly validating and optimizing the performance of the platform, the ZZ-CSQ platform can rapidly purify therapeutic antibodies from industrial harvest feedstock with high purity (>97%) and recovery yield (95% ± 3%). In addition, the ZZ-CSQ platform outperforms protein A-based affinity chromatography (PAC) in removing impurities, yielding ∼20-fold less DNA and ∼4.8-fold less host cell protein (HCP) contamination. Taken together, this platform is rapid, recyclable, scalable, and cost-effective, and it shows antibody-purification performance superior or comparable to that of the standard affinity chromatography method.
Bibliographical noteFunding Information:
This work was supported by the Samsung Research Funding and Incubation Center of Samsung Electronics under Project Number SRFC-MA1801-07 (S.K.) and SRFC-MA1501-51 (S.J.). We thank Samsung Bioepis for kindly providing industrial harvest feedstock, Prof. Gyun Min Lee at Korea Advanced Institute of Science and Technology for providing cell culture medium containing trastuzumab, and Dr. Yunhee Seo at Korea Institute of Science and Technology for providing support for TEM observations.
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ASJC Scopus subject areas
- Analytical Chemistry