The Importance of Dynamic Binding Capacity (DBC) in mAb Purification
There is now greater pressure on downstream purification processes to meet the demand from increased cell titers. But how can you meet this demand without negatively impacting your manufacturing footprint and process economy? The solution may lie in your choice of protein A resin.
We look at the importance of dynamic binding capacity as an attribute of effective protein A resins in mAb purification and how this can help reduce your downstream processing bottlenecks.
Downstream purification of monoclonal antibodies (mAbs)
If you’re working in the purification of monoclonal antibodies, you will already be aware of the bottlenecks in downstream processing brought on by mAb production and the increase in cell titers. Large scale processes are feeling the impact of these bottlenecks and for many, increasing column sizes to help with manufacture limitations comes with unwanted economic costs. The need for more efficient manufacturing processes is now evident and purification operations must react quickly to avoid limiting their throughput.
Protein A affinity chromatography continues to be the optimal method of mAb purification due to its high selectivity that allows for exceptional purity. The protein A resins used in this process feature an agarose-base matrix and demonstrate great hydrophilicity, increasing the surface area of the bead which in turn improves the binding capacity (Why Agarose?). Traditionally, these protein A resins had a low capacity and came at a high cost. But as demand for purified monoclonal antibodies increases, it is becoming clear that a more efficient protein A resin will be a prerequisite of all future mAb purification processes.
What is Dynamic Binding Capacity (DBC)?
Dynamic Binding Capacity (DBC), in relation to mAb purification, refers to the amount of protein that binds to the resin under specified flow conditions before a substantial breakthrough of unbound protein is observed. Having a good binding capacity means that your resin can capture mAbs at a wide range of flow velocities, resulting in enhanced productivity. The DBC determines how much resin will be required to purify a specific amount of protein, making it an important characteristic to consider when choosing a suitable protein A resin.
The difference between high and low dynamic binding capacity
Due to several variable factors involved in the purification process, a high or low dynamic binding capacity can be achieved.
- Low Dynamic Binding Capacity: A loss of protein during the application
- High Dynamic Binding Capacity: A slight loss of protein during the application
Why is this important?
High dynamic binding capacity allows you to load large amounts of protein onto the column. With a high DBC, you only require a small amount of resin to bind a lot of protein at a high flow rate. This removes the need to invest in larger columns and more resin in order to bind the same amount of protein. In order to achieve a higher dynamic binding capacity, low flow rates are required to give longer residence time. The prolonged time in which the protein is in contact with the resin, utilizes the full capacity of the resin. This is crucial to attaining higher productivity.
Benefits of a high dynamic binding capacity
The benefits of using more efficient protein A resins with a high dynamic binding capacity are evident when evaluating the impact, or lack thereof, that they have on your existing purification processes.
Process Economy
Using protein A resins with enhanced binding capacities shows profound benefits for your process economy. The reduction in the amount of resin required to purify the mAbs is key. This decreases buffer consumption significantly, which saves on preparation costs and allows existing equipment to be used for processing. This enables you to achieve a better throughput from the same manufacturing footprint.
Performance & Productivity
A high binding capacity at a shorter residence time and a higher flow rate will allow you to bind more of your target protein. The resin should also display high mechanical stability and low non-specific binding of impurities. Innovations to the resin beads aid in increasing binding capacity. Using smaller and more porous beads, the accessible surface area of the resin is increased and allows for more protein to be eluted.
How to determine dynamic binding capacity
In order to optimize your purification process, it is highly recommended that the binding capacity is determined for the target protein in experimental conditions.
The dynamic binding capacity can be determined by loading a sample of the target protein and monitoring the flow-through until the protein reaches breakpoint, and unbound protein flows through the column. This will generate a breakthrough curve, allowing you to observe the maximum amount of protein that can be loaded onto your column. The amount of protein that has been adsorbed at 10% of this curve is what is usually considered the dynamic binding capacity.
When working in affinity chromatography, it is recommended that you run your own tests to determine the DBC for your specific target protein.
Below: A graph depicting the dynamic binding capacity of our Praesto® Jetted A50 resin at 10%.
