Ask the Expert: Frank Detmers
Taking Protein Purification to the Next Level
CaptureSelect™ products are affinity ligands created through a proprietary technology based on camelid-derived single-domain antibody fragments. The ligand is a 12 kDa single-domain fragment (VHH) that comprises the 3 CDRs that form the antigen-binding domain, efficiently produced in yeast.
Designed for stability, affinity, and selectivity, CaptureSelect™ products offer the benefits of reduced cost of purification, higher quality product, and increased flexibility in the purification process. These features make CaptureSelect™ products a preferred tool for bioseparation and life science applications.
Below is an exclusive interview with our CaptureSelect™ technology expert on why it is superior and a great platform for manufacturing biosimilars.
What are CaptureSelect™ affinity products, and what’s unique about them?
CaptureSelect™ products contain affinity ligands based on heavy chain antibodies. Most antibodies consist of both heavy and light chains, but camelids have only the heavy chain. They can recognize an antigen with high affinity. The CaptureSelect™ ligands are based on the variable domains of heavy chain antibodies which are small proteins, at about 12-15 kDa. Because they’re smaller, they can’t be as easily denatured.
What’s the advantage of a smaller antibody?
They are more stable compared to other traditional monoclonal antibodies, because of their small size and single chain. They also can be reused. Therefore, the lifetime of a column is longer; you can do multiple runs on the same material. Domains that can’t be reached by classic antibodies can be reached by the CaptureSelect™ ligand. We can also develop ligands for unique domains. For example, IgG CH1 has no classical antibodies directed at that domain. But we have a ligand that can recognize human IgG at the CH1 domain. That’s a real unique feature that shows the advantage of using a small ligand.
Can this work for purification of biosimilars?
Yes, this is a great platform for biosimilars. We have ligands specific for FSH, Human Growth Hormone (HGH), albumin, and IgG Fc fusion proteins. If you have a specific capture step in a given process, basically all the steps downstream are aimed at creating your final product. In fact, you have a comparable process for purification of all biosimilars; once you put the right capture step in place, the rest of your purification scheme can be the same. The CaptureSelect™ technology opens up a platform approach to purify different kinds of proteins, including therapeutic proteins. By having the whole purification train intact, including the capture step, it will be applicable for any protein.
How do ligands and resins work?
The ligand is first immobilized on a solid support (often a resin). This can be any support that is chemically activated. The interaction of ligand and target protein is based on the antigen-antibody reaction. The ligand will have a high affinity (low nanomolar range) for the target protein and during the ligand discovery and screening process we can screen for binding and elution conditions that can be applied in the process. For example, our FSH ligand binds and elutes, and no pH shocks are involved. That’s important because FSH isn’t stable at lower pH, so you get a better yield and higher purity without the pH shock, all in a single chromatography step.
How many specific ligands do you have now?
We have 30 different resins for R&D. For bioprocessing on larger scales, we have about 10 products that can be delivered at any scale. We also offer many of these resins prepacked into columns, for analytical use, such as titer evaluation.
What are the disadvantages of Protein A?
Sometimes, it’s not clear whether Protein A is going to work. If you make changes in to a CH3 or CH2 domain of human IgG, and you only have protein A to bind to it, Protein A might not bind anymore. If you use the Capture Select™ technology, you can select the domain of the antibody that you are going to use for purification. In addition, elution conditions are milder compared to Protein A.
Do you offer custom service?
Yes, we can select, identify and develop a ligand for a specific protein that a customer wants to purify. We can also design scavenging applications for an impurity they can’t get rid of. We’ll scavenge for that impurity while the protein isn’t binding to this specific ligand. We can offer ligands on different kinds of platforms, too, including POROS® resins and prepacked analytical columns. The ligand can also be biotinylated—to measure with ELISA, Octet, BiaCore, and conduct label-free analysis.
CaptureSelect™ Ligand Application,
In 2001, Frank Detmers received his PhD in molecular microbiology from the University of Groningen, The Netherlands. From 2001 until 2004, he worked as a postdoctoral researcher at the Department of Cell Physiology, Nijmegen Center of Molecular Life Sciences. He joined BAC BV (Leiden, The Netherlands) in 2004. His work focuses on immobilization of affinity ligands on solid supports and the development of new applications for CaptureSelect™ ligands. Currently, Frank is director of ligand application at BAC, which became part of Life Technologies in January.