Learn how to use this product The IBA Strep-tag detection system offers a choice between HRP- or AP-labeled Strep-Tactin for direct detection and non-labeled antibodies to be detected by a secondary antibody. Fast detection is possible with the Strep-Tactin conjugates whereas monoclonal antibody-based detection enables higher specificity. StrepMAB-Immo is a murine monoclonal antibody with a high affinity to Strep-tag® and Twin-Strep-tag® fusion proteins. It is well-suited for the immobilization of tagged proteins on solid phases (SPR sensor chips) and the detection in applications like FACS, ELISA, immunohistochemistry, or immunocytochemistry. Strep-tag® proteins with an N-terminal Serine-Alanine linker (protein-SA-WSHPQFEK or SA-WSHPQFEK-protein) are validated for nearly irreversible binding. Proteins with other N-terminal sequences bind with a reduced affinity. The Twin-Strep-tag® always carries the N-terminal SA linker (WSHPQFEK-GGGS-GGGS-GGSA-WSHPQFEK). For detection of Strep-tag®II or Twin-Strep-tag® fusion proteins in Western Blots, it is recommended to use StrepMAB-Classic or Strep-Tactin® conjugates.