Biotin

Biotin is a water-soluble B-complex vitamin, also known as vitamin B7 or vitamin H. It binds to the biotin-binding pockets of streptavidin, Strep-Tactin®, and Strep-Tactin®XT with different affinities. As a result, it allows the efficient elution of Strep-tag®II or Twin-Strep-tag® fusion proteins from Strep-Tactin®XT, while maintaining the reusability of the resin. It can be used for preparation of Strep-Tactin®XT elution buffer, Buffer BXT. In addition, biotin can be used for elution of biotinylated proteins from Strep-Tactin®, where it binds irreversibly to the resin. Hence, Strep-Tactin® cannot be regenerated in this kind of application.