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Protein A affinity chromatography for superior protein purification

Protein A affinity chromatography

Protein A affinity chromatography is an essential step in monoclonal antibody (mAb) purification.  Efficient capture and impurity removal have an outsize impact on the productivity and efficiency of subsequent purification steps.

Amsphere® A+ is a Protein A resin with a ligand engineered to maximize binding capacity at short residence times (RT). In addition, surface bead modifications enhance impurity removal. This advanced resin has excellent durability and caustic stability and provides the performance needed for high-titer and intensified fed-batch or continuous processes.

Key takeaways:

Amsphere® A+ is a Protein A resin engineered for high dynamic binding capacity (DBC) and improved caustic stability making it well suited for efficient mAb capture during high-titer and intensified mAb manufacturing processes. Key performance characteristics include:
  • Outstanding DBC: DBC10% of ≥62 mg/mL at 5 min residence time which is higher than Amsphere® A3 resin and higher or equivalent to market-leading agarose-based Protein A resins
  • Superior Pressure-Flow Properties: Consistent pressure-flow behavior across bed height (BH) of 10 to 25 cm, supporting scalability from laboratory to process scale

Key specifications of Amsphere® A+ resin:

  • Base bead: Methacrylic copolymer, average particle size (d50): ~60 µm
  • Ligand: Recombinant Protein A expressed in Escherichia coli
  • Dynamic binding capacity (DBC10%) : ≥70 mg/mL at 6 min residence time (RT), ≥60 mg/mL at 4 min RT, ≥50 mg/mL at 2 min RT
  • Alkali stability: 94% DBC after 24 hours in 1M NaOH, 91% DBC after 300 cycles with 0.1 M NaOH (15 min. contact time)

Visit our Affinity chromatography resin page for more information on our affinity chromatography portfolio.

Chromatography

Test material was a sterile-filtered, clarified mAb harvest loaded onto a 0.5 cm internal diameter (ID) x 2.5 cm bed height (BH) column packed with Protein A resin. Residence time for all steps apart from load was 2 min.

High dynamic binding capacity at short residence times

High DBC at short residence times improves productivity and speeds up mAb purification.

Clarified harvest of mAb 1 (pI 8.2, 5.2 mg/mL) was used as the test material to evaluate the dynamic binding capacity (DBC10%) of Amsphere® A+ and other market-leading agarose resins following the approach described in the experimental overview.

At a 1 min residence time (RT), Amsphere® A+ resin had the highest binding capacity of the resins evaluated with a DBC10% of 54 mg/mL, Figure 1. By comparison, Amsphere® A3 resin achieved 49 mg/mL, while the DBC10% of Amsphere® A+ resin was ~30 % higher than the other market-leading resins evaluated.

Bar chart comparing dynamic binding capacity at 10% breakthrough of Amsphere® A+, Amsphere® A3 and market-leading agarose-based Protein A resins A and B with mAb 1 at 1 min RT. Amsphere® A+ resin shows higher dynamic binding capacity at 10% breakthrough than other resins at ~54 mg/mL.

Figure 1.DBC10% of market-leading Protein A chromatography resins at 1 min residence time.

Binding capacity of the four resins was evaluated at RT of 1, 2 and 5 min using the same mAb 1 clarified harvest, Figure 2. At 1- and 2- min RT, Amsphere® A+ resin showed higher DBC10% than all other resins tested. At the longer 5 min RT, binding capacities of market-leading resins A and B resins were comparable to that of Amsphere® A+ resin.

Dynamic binding capacity at 10% breakthrough of Amsphere® A+ resin and other market-leading Protein A chromatography resins at RT of 1, 2 and 5 min.  Amsphere® A+ resin demonstrated dynamic binding capacity at 10% breakthrough values of ≥54, ≥59 and ≥62 mg/mL, respectively which was equivalent to or higher than other resins.

Figure 2.DBC10% of Amsphere® A3 and market-leading Protein A resins at different RT.

Improved impurity clearance with Amsphere® A+ resin

Impurity clearance capabilities of the Protein A resins were compared with the same mAb 1 harvest material at a 1 min RT (Figure 3).

Amsphere® A+ resin demonstrated comparable host cell protein (HCP) clearance and DNA clearance to other market-leading Protein A resins.

Bar charts showing levels of HCP (A) and DNA (B) for Amsphere® A+ and Amsphere® A3 resins and other market-leading Protein A chromatography resins. Amsphere® A+ resin demonstrated comparable performance to the other resins.

Figure 3.Levels of A: HCP and B: DNA in elution pools of market-leading Protein A chromatography resins.

Easy scalability with superior pressure flow profile

The methacrylic resin-based matrix of Amsphere® A+ resin enables high flow rates resulting in shorter loading times and improved productivity. This matrix enables scalable, high flow velocity from small to process scale, Figure 4.

Delta-column pressure (bar) versus linear flow rate in (cm/hr) of Amsphere® A+ resin packed in columns with BH of 10, 15, 20 and 25 cm.

Figure 4.Delta-column pressure versus linear flow rate for columns with different BH containing Amsphere® A+ resin.

Frequently asked questions

The chromatography business of JSR has recently been acquired and we are in the process of integrating these well-established affinity resins into our Process Solutions portfolio, strengthening our Protein A chromatography capabilities with best-in-class products.

In the short term you can use the form on the website or reach out to your account representative.

Amsphere® Protein A resins are used for the affinity capture of monoclonal antibodies (mAbs) and their derivatives in biopharmaceutical manufacturing. Amsphere® A+ is designed for high-titer and intensified processes, including concentrated fed-batch and continuous bioprocessing, where maximum dynamic binding capacity at low residence times and long-term caustic stability are critical. Amsphere® A3 is an established platform resin suited for a broad range of mAb capture applications, offering a well-balanced productivity and cost-of-goods profile, and is a proven choice for dual sourcing strategies.

Both Amsphere® A3 and Amsphere® A+ are Protein A affinity resins designed for mAb capture, but they are optimized for different process strategies. Amsphere® A3 is an established platform resin offering consistent, reproducible performance across a broad range of mAbs and their derivatives, with a well-balanced productivity and cost-of-goods profile. It is well-suited for scalable platform processes and is a proven choice for dual sourcing strategies. Amsphere® A+ is optimized for maximum productivity in high-titer and intensified processes, delivering outstanding dynamic binding capacity at low residence times. Its exceptional caustic stability and long cycle lifetime make it the right choice for concentrated fed-batch and continuous bioprocessing platforms where process demands are high.

The choice between Amsphere® A3 and Amsphere® A+ depends on your specific process requirements. If you are running a standard mAb capture process and are looking for a reliable, scalable platform resin with a well-balanced productivity and cost-of-goods profile, Amsphere® A3 is the right choice. It is also well-suited for dual sourcing strategies, offering a qualifiable alternative that reduces single-supplier risk. If your process is high-titer or intensified, such as concentrated fed-batch or continuous bioprocessing, and maximum dynamic binding capacity at low residence times is a key requirement, Amsphere® A+ is the recommended option. Its exceptional caustic stability and long cycle lifetime further support the extended resin reuse demands of intensified and continuous manufacturing operations.

For intensified processing, Amsphere® A+ is the recommended Protein A resin. It is specifically engineered to meet the process demands of high-titer and intensified manufacturing modes, including concentrated fed-batch and continuous bioprocessing, delivering outstanding dynamic binding capacity at low residence times. Its exceptional caustic stability and long cycle lifetime ensure reliable performance across extended resin reuse, which is a critical requirement in both intensified batch and continuous manufacturing operations.

For mAb capture in a standard batch process, Amsphere® A3 is the recommended choice. It is an established platform resin offering consistent, reproducible Protein A capture performance across a broad range of mAbs and their derivatives. Its well-balanced productivity and cost-of-goods profile makes it well-suited for platform process strategies that prioritize operational robustness and scalability. Amsphere® A3 is also a proven choice for dual sourcing strategies, providing supply security without compromising process performance.

Amsphere® A+ and Amsphere® A3 will be included in the Emprove® Program soon. Until then, please reach out to your local Merck representative for comprehensive documentation packages and support with qualification, risk assessment, and regulatory activities.

Yes. Amsphere® Protein A resins are specifically designed for the capture step in monoclonal antibody (mAb) purification. For downstream purification steps beyond capture, additional chromatography technologies such as mixed-mode resins and membrane-based solutions are used to address impurity removal and polishing requirements.

Amsphere® Protein A resins use a rigid synthetic methacrylic copolymer base bead instead of a soft agarose matrix. This provides higher mechanical and chemical stability, enabling faster flow rates, taller bed heights, stable pressure drop, high dynamic binding capacity at short residence times and long resin lifetime, all of which lower the cost per gram of purified antibody.

Dual sourcing is a supply chain strategy in which two qualified resin suppliers are maintained for the same process step, ensuring that manufacturing can continue uninterrupted in the event of supply disruptions, quality issues, or regulatory holds with one supplier. For biopharmaceutical manufacturers, qualifying a second Protein A resin reduces single-supplier dependency and strengthens overall supply chain resilience, which is increasingly important in a global manufacturing environment. Amsphere® A3 is an established choice for dual sourcing qualification, offering consistent, reproducible Protein A capture performance across a broad range of mAbs and their derivatives, with a well-balanced productivity and cost-of-goods profile that supports straightforward process comparability.

Caustic stability refers to a resin's ability to withstand cleaning-in-place with sodium hydroxide (NaOH) solutions, which are the industry standard for sanitization between purification cycles. A resin with high caustic stability maintains its dynamic binding capacity and structural integrity across many cycles of NaOH exposure, ensuring consistent process performance over the resin lifetime. This is particularly critical in high-cycle processes such as continuous bioprocessing or intensified fed-batch manufacturing, where resins are subjected to frequent and aggressive cleaning regimens. High caustic stability directly translates into extended resin reuse, reduced resin replacement frequency, and lower cost-of-goods per gram of purified product.

Amsphere® resins contribute to improved cost of goods through two key factors: high dynamic binding capacity and long resin lifetime. A high dynamic binding capacity at low residence times allows more product to be captured per cycle and per liter of resin, reducing the required resin volume and column size for a given production output. The exceptional caustic stability of Amsphere® resins supports extended resin reuse across many cycles with aggressive cleaning-in-place protocols, reducing the frequency of resin replacement and spreading the resin investment across a higher number of purification cycles. Together, these properties enable a more productive and cost-efficient capture step, contributing to a favorable cost-of-goods profile across the resin lifetime.

Why Merck: technical expertise, regulatory support

Our technical and application experts are ready to support your process development, implementation, and scale-up. The Emprove® Program provides comprehensive technical, regulatory, and supply information to help streamline qualification, risk assessment, and compliance.

Process development and manufacturing support

Partner with our process development scientists and MSAT team at the M Lab™ Collaboration Center to optimize and scale your chromatography operation. Either in person or virtual visit, we can help develop, test or troubleshoot without disrupting your manufacturing schedule. Customer Collaboration Labs for Bioprocessing Optimization

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