Contrasting Dynamic Binding Capacity Across Affinity Resins


Overview

Protein A affinity resins are most commonly used to perform the capture step in therapeutic drug purification workflows. However, this step contributes significantly to the overall production cost of protein purification. 

To reduce production costs, high-capacity protein A resins are preferred as they bind more efficiently to the target molecule. Unsurprisingly, dynamic binding capacity (DBC) is a critical consideration when adopting a protein A resin for monoclonal antibody (mAb) purification.

This study compares the DBC of two PuroliteTM protein A resins and two competitor products for the purification of three classes of antibody-related molecules.

Figure 1 Dynamic Binding Capacity Comparison - DBC comparison across four resins using an Fc-fusion protein (blue), a standard mAb (orange), and a bispecific antibody (green).
Investigation

In this investigation, the DBC of two Purolite protein A resins were compared to two competitor offerings.

The first resin, Purolite™ Praesto™ Jetted A50, is a native protein A resin, designed to purify a wide range of mAb constructs. The second resin, Purolite™ Praesto™ Jetted A50 HipH, allows for the elution of the bound monoclonal antibody molecule at a milder pH. This resin is particularly suited for complex purification procedures, including pH-sensitive antibodies prone to aggregation at typical pH elution levels.

To form a comparison, two competitor resins were also investigated. Competitor A is a widely used native protein A resin, and Competitor B is an engineered high-performance protein A resin.

To evaluate performance across a wide range of antibodies, the  DBC of each resin was investigated when used for the purification of three different molecule types: Fc-fusion, pH-sensitive mAb, and bispecific. The results are shown in figure 1.
  • Fc-fusion molecule: Antibody where the Fc region is combined with another protein.
  • mAb: A standard monoclonal antibody.
  • Bispecific: IgG1 bispecific with two binding sites on either antibody ‘arm,’ targeting different molecules.

Conclusion

The study demonstrated the consistency of Purolite Praesto Jetted A50 across traditional and complex molecules, with DBC comparable to both competitor resins widely used in the bioprocessing market. Purolite Praesto Jetted A50 HipH gave the best DBC for the bispecific antibody, where milder pH elution reduced aggregation compared to traditional protein A resins.

This DBC comparison study demonstrates the comparable performance of Purolite resins across three differing but related molecular structures, illustrating the versatility of the Purolite affinity resin toolbox for traditional and complex antibody therapeutics.