Learn how to use this product The Strep-Tactin®XT 4Flow gravity flow columns can be used for the purification of proteins that have been tagged with Strep-tag®II or Twin-Strep-tag®. These fusion proteins specifically bind to the high-affinity Strep-Tactin®XT ligand, producing highly pure target proteins (>95%). It is recommended for challenging and low abundant proteins because of its stability and low agarose concentration. For proteins with increased affinity, like multimeric proteins, Strep-Tactin® resins are recommended for easier elution. When working with large sample volumes, the application aid WET FRED is recommended to reduce the waiting periods during the sample and buffer application.