The CaptureSelect C-tag system also allows binding of the protein-of-interest under denaturing conditions. Once the protein is bound to the resin in the presence of a denaturant (e.g., 8 M urea), the affinity resin can then be incubated with a suitable buffer to allow on-column re-folding prior to elution.
The CaptureSelect C-tag affinity resin can be used in a packed-bed format as well. The chromatogram in Figure 3 demonstrates the purification of a camelid domain antibody equipped with a C-terminal GAA-EPEA tag (MW 14.9 kDa, DBC ≈ 1.7 mg/mL).
In addition to the CaptureSelect C-tag affinity resin, the anti-C-tag affinity ligand is also provided as conjugated ligand (e.g., conjugated to Biotin). This facilitates easy detection and or quantitation of EPEA C-tagged proteins using techniques such as ELISA, Western blot, and label-free platforms (Biacore and Octet).
In summary, the EPEA tag, in combination with the CaptureSelect C-tag affinity matrix, is providing an alternative to existing technologies to facilitate the routine purification and analysis of proteins during R&D.