Recombinant Protein Purification using Strep-Tactin®XT
IBA’s 3rd generation Strep-tag® system is based on the Strep-Tactin®XT resin in combination with Twin-Strep-tag® and is one of the most widely used purification systems for recombinant proteins. Due to a binding affinity of Strep-Tactin®XT to Twin-Strep-tag® in the low pM range (near covalent binding!), the system is superior to all other available affinity purification systems and can be used for a wide variety of applications, e.g. protein purification and assay development.
Strep-Tactin®XT provides superior performance in the field of high throughput screening, batch purification, purification using denaturing conditions and protein interaction studies. Furthermore higher protein yields compared to Strep-Tactin® are obtained. Simultaneously, Strep-Tactin®XT preserves all benefits of Strep-Tactin® for protein purification, e.g. high purity (> 95 %), physiological buffer conditions, mild elution, regeneration of the resin for re-use.
Get highly pure proteins with Strep-Tactin®XT resin
One of the key advantageous of the Strep-tag® system is to achieve unparalleled protein purity (> 95 %) after purification of recombinant proteins independent of the expression host. This makes the system advantegous to other affinity purification systems like His-tag.
The 3rd generation Strep-tag® system with its new features makes it suitable for additional applications:
|New applications:||Excellent performance:|
Besides the purification of classical proteins the Strep-tag® system should be the method of choice for:
- membrane proteins
- low abundant proteins (in combination with Strep-Tactin®XT)
- sensitive protein complexes with multiple subunits
- bioactive proteins
- and any other protein
The Streptavidin:Biotin binding is the strongest noncovalent biological interaction known. With IBA's newly developed Strep-Tactin®XT in combination with Twin-Strep-tag®, this high binding affinity can be used for e.g. protein purification, protein interaction analysis or assays (e.g. BIAcore). Since Biotin is still binding strongly to Strep-Tactin®XT it can be used for elution of Twin-Strep-tag® fusion proteins.
Purification of target proteins in a simple one-step purification cycle:
Step 1: The cell lysate / culture supernatant is applied on the column.
Step 2: Once the tagged protein has bound specifically to Strep-Tactin®XT the host proteins are instantly washed away with moderate amounts of physiological wash buffer (Buffer W).
Step 3: Bound Twin-Strep-tag® protein is gently eluted by Buffer BXT (wash buffer containing 50mM biotin) which specifically competes for the biotin binding pocket.
Step 4: Regeneration of the column is achieved by the application of 3 M MgCl2. Magnesium chloride removes the biotin from the binding pocket. MgCl2 can be removed simply by applying Buffer W. Instead of MgCl2, freshly prepared 10 mM NaOH can also be used. Strep-Tactin®XT resin can be regenerated and re-used 3 to 5 times without loss in performance.
Strep-tactin®XT can be used in combination with the following tags:
- 8 amino acids
- sequence: Trp-Ser-His-Pro-Gln-Phe-Glu-Lys (WSHPQFEK)
- 28 amino acids (WSHPQFEK-GGGSGGGSGG-SA-WSHPQFEK)
- Two Strep-tag®II motifs in series
- Higher affinity than Strep-tag®II
Features of both tags
- Fusion to the N- or C-terminus
- No influence on protein folding and function
- No removal necessary