StrepMAB-Immo is a murine, high-affinity monoclonal antibody, which is especially suited for stable, mild, and oriented capturing of Strep-tagII and Twin-Strep-tag fusion proteins on solid phases (e.g. Biacore CM5 sensor chips) or for detection of those proteins in applications like ELISA, FACS, immunohistochemistry, and immunocytochemistry. The nearly irreversible binding is validated for fusion proteins carrying a C- or N-terminal Strep-tagII providing an N-terminal extension by a SerAla linker (recombinant protein-SA-WSHPQFEK or SA-WSHPQFEK-recombinant protein). Proteins containing the Strep-tagII with N-terminal sequences other than SerAla are bound with reduced affinity in the cases tested so far. However, the Twin-Strep-tag always contains the SerAla linker (WSHPQFEK-GGGS-GGGS-GGSA-WSHPQFEK). Please note: For detection of Strep-tagII or Twin-Strep-tag fusion proteins in western blots, the use of StrepMAB-Classic or Strep-Tactin is recommended.