For more than 20 years, IBA Lifesciences has been offering high-performance life science products for the academic research world and industry. High-performance research tools for protein and cell isolation based on proprietary Strep-tag® technology.


Protein affinity chromatography

In order to purify a protein using its affinity to another molecule, the interaction partner (ligand), e.g. a protein, a small molecule or a metal, is immobilised on the stationary phase of the chromatography matrix. The stationary phase usually consists of agarose or synthetic polymers and is packed into a column in the form of beads. The beads are surrounded and moistened by a liquid, the so-called mobile phase. When the target protein-containing sample is applied, it enters the mobile phase and passes through the beads of the stationary phase. Meanwhile, the target protein can bind to the ligand, while other molecules remain in the mobile phase and can be removed by washing. To elute the target protein, the interaction with the ligand is dissolved by changing the buffer conditions, e.g. the pH, or by adding a specific competitor that displaces the target protein from the ligand, which leads to dissociation of the target protein while the ligand remains immobilised on the stationary phase.


Protein purification with unknown interaction partner

These protein purification strategies utilise the affinity of known interactions to indirectly capture the target protein. For this purpose, the target protein is labelled with a short peptide of a known interaction partner that is able to bind to an immobilised partner on the stationary phase.

The short peptide is called an affinity tag and can be a His-Tag, GST-Tag, Strep-Tag®II or Twin-Strep-Tag®, for example. They can bind to ligands such as metal ions, glutathione, Strep-Tactin® or Strep-Tactin®XT.

Principle of protein affinity chromatography


Affinity-based systems: one of the most important protein purification methods

However, some of the widely used affinity tags, such as the His tag, have several drawbacks and limitations, as they can alter the natural conformation of the target protein or require stringent elution and washing conditions that reduce the yield of the target protein. In addition, many tags are not compatible with some buffers and must be removed in order not to interfere with downstream processes.

The widely used Strep-tag® technology, consisting of the two streptavidin variants Strep-Tactin® and Strep-Tactin®XT as well as the two affinity tags Strep-tag®II and Twin-Strep-tag®, is not restricted with regard to buffer types and leads to the recovery of high-purity proteins due to its high specificity.

IBA Lifesciences offers various matrices coupled with either Strep-Tactin® or Strep-Tactin®XT, all of which are suitable for the purification of Strep-tag®II and Twin-Strep-tag® fusion proteins. The purification cycle varies between the two Streptavidin variants, but both matrix types serve the same purpose: simple and fast protein purification