Strep-tag Antibody

• Excellent results in dot- and western-blotting procedures
• Highly sensitive and specific detection

The Two-Step Affinity Purification System, which is based on the proven 6xHis tag and the short Strep-tag II, enables simple and highly efficient purification of ultrapure proteins in a fast and standardized procedure. Recombinant proteins carrying both tags are purified sequentially on Ni-NTA and Strep-Tactin matrices (see figure  Ultrapure protein in two steps). The two simple affinity purifications provide fully active, full-length, ultrapure protein, suitable for any downstream application.

Recombinant proteins that carry two small affinity tags (the 6xHis tag and Strep-tag II) are efficiently expressed in E. coli, insect, or mammalian cells using pQE-TriSystem His·Strep vectors. After cell lysis and clearing of the lysate, proteins are initially purified using an immobilized-metal affinity chromatography procedure that is based on the proven 6xHis-tag-Ni-NTA interaction. After elution from the Ni-NTA matrix using imidazole, recombinant proteins (which also carry the Strep-tag II epitope) are loaded directly onto a Strep-Tactin matrix. No buffer exchange is required. Protein is eluted from the Strep-Tactin matrix using either biotin or desthiobiotin. This two-step affinity purification delivers ultrapure (>98% pure) protein (see figure  Two-step affinity purification procedure). The order of purifications can be reversed (i.e., Strep-Tactin followed by Ni- NTA purification). Proteins can be detected with high specificity and sensitivity using mouse monoclonal Strep-tag or Anti·His antibodies.

The two-step affinity purification system, using the Strep-tag Antibody for detection, is highly suited for applications where high purity is at a premium or is difficult to achieve. The standardized purification procedure also increases throughput by eliminating the need for protein-specific purification protocol development and optimization. The ultrahigh purity and convenience provided by the two-step affinity purification system make it the method of choice for:

• Structural and functional analyses
• Expression in eukaryotic systems