Recombinant Strep-Tactin with Cysteine

Mol. Wt.: Subunit 13.4 kDa; Tetramer 53.6 kDa

Theory pI: 8.12

Theoretical Activity: 18.2 U/mg protein (r-STc:Biotin = 1:4(mol:mol))

Activity: ≥15 U/mg protein（Green improved method）

Purity: ≥95%（SDS-PAGE）

A280nm(1 mg/mL): 3.13

Endotoxin: ≤5EU/mg

Storage Condition: -20 ℃

Storage Duration: 3 years

Description:

Strep-Tactin is a mutant of streptavidin, which can specifically bind to the Strep II tag. The Strep II tag is a small tag of 8 amino acids (WSHPQFEK). As the tag is small, and have a molecular weight of 1kDa, which generally does not affect the structure and function of the fusion protein, commonly used in the detection and purification of fusion protein. Compared with streptactin, the affinity of Strep-Tactin and Strep II tag has more than 10 times stronger than the affinity streptavidin and Strep II tag. Strep-Tactin  can bind and dissociate with streptavidin in mild conditions, and can play a great role in separation and purification when bonded with medium. In order to be able to bond to the medium, a cysteine was added at the C-terminal of amino acid sequence, which can be covalently bonded to the medium by sulfhydryl group.

M:Protein Molecular Weight Marker

Lane 1:r-STc Subunit  Lane 2:r-STc  Tetramer 

For research use only！