The streptavidin variant Strep-Tactin® as conjugate with horseradish peroxidase (HRP) for fast and directed detection of N-terminally, C-terminally, or internally tagged Strep-tag®II or Twin-Strep-tag® fusion proteins transferred to a blotting membrane. Strep-Tactin® HRP is suitable for chromogenic and chemiluminescent reactions.
Depending on the host organism, protein extracts may contain small amounts of biotinylated proteins, e.g., the biotin carboxyl carrier protein (BCCP, 22 kDa ) of E. coli. Biotin Blocking Buffer is recommended for blocking of such biotinylated proteins on western blots prior to detection of Strep-tag®II or Twin-Strep-tag® fusion proteins with Strep-Tactin® HRP to prevent the detection of false positive bands. For this purpose, Biotin Blocking Buffer contains the tetrameric biotin binding protein avidin, which selectively binds biotinylated proteins.