Streptavidin is a streptavidin mutant, which can bind specifically to streptavidin. The Strep II tag is a small tag of 8 amino acids (wshpqfek). Since the tag is small, it is only about 1 kDa in size, which generally does not affect the structure and function of the fusion protein. It is commonly used in the detection and purification of the fusion protein.
Compared to streptavidin, streptavidin has a 10 times stronger affinity for streptavidin. It can bind and dissociate with streptavidin under mild conditions and can play a good role in separation and purification. The amino acid sequence of this product does not contain cysteine and can be covalently linked in the middle through amino, carboxyl, and other groups in the protein molecule.
The Strep•Tag II/Strep Tactinsystem combines high specificity with gentle elution conditions to provide highly purified, potentially active, recombinant proteins, or protein complexes, after a single purification step. The system includes a variety of vectors, purification products, and detection reagents for rapid affinity purification.
The Strep Tag system is based on reliable biotin/streptavidin binding specificity. The small Strep Tag II peptide is an eight amino acid fusion tag with binding specificity comparable to biotin. The small size of the tag reduces potential interference with the target protein structure or function. The tag binds to Strep Tactin protein.
which is an engineered streptavidin with an optimized Strep Tag II peptide binding site. The Strep Tag II peptide binds to Strep Tactin protein nearly 100 times tighter than it binds to streptavidin but elutes under gentle, physiological conditions. Rapid, one-step affinity purification of Strep Tag fusion proteins can result in active proteins at greater than 95% purity.
In a comparison of affinity tags, the Strep Tag peptide was shown to provide excellent purification, with good yields, at a moderate cost (1). The Strep•Tag system includes Strep Tag II vectors (for expression in bacterial, insect, or mammalian cells), a wide range of Strep•Tactin affinity purification resins, hardware, and buffers, and Strep Tag detection reagents.