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Protein Production & Assays

The Strep-tag® system is based on one of the strongest non-covalent interactions in nature, which is the interaction of biotin to streptavidin. It allows the purification, detection and immobilization of recombinant proteins. The system includes two affinity tags: Strep-tag®II and Twin-Strep-tag®. This peptide sequences exhibit intrinsic affinity towards Strep-Tactin® and Strep-Tactin®XT, two specifically engineered streptavidin variants.

By exploiting the highly specific interaction, Strep-tagged proteins can be isolated in one step from crude cell lysates in unparalleled purity. Because the Strep-tag® elutes under gentle, physiological conditions it is especially suited for generation of functional proteins e.g. enzymatic proteins. The mild (physiological) purification and elution conditions required for Strep-tag® fusion proteins make them suitable for structural and functional investigations, protein-protein interaction studies, ligand-receptor investigations or even separation of living cells for re-culturing processes. The system is suitable for multiple protein classes, e.g. metallo proteins, membrane proteins, fragile protein complexes with multiple subunits and any other protein class.

In addition, the near covalent affinity of Twin-Strep-tag® to Strep-Tactin®XT can be used to efficiently immobilize proteins for assay development. This makes the system to a universal platform and superior to all other affinity systems: one tag can be used for expression, purification, detection and immobilization.