Strep-Tactin® Buffer Set contains all buffers necessary for purification of Strep-tag®II or Twin-Strep-tag® fusion proteins with Strep-Tactin® as well as for subsequent regeneration of the resin. Buffer W (10x) is a 10x concentrated wash buffer for Strep-Tactin® and Strep-Tactin®XT resins. It removes unbound molecules from the affinity chromatography matrix during Strep-tag®II and Twin-Strep-tag® fusion protein purification. Buffer E (10x) is a 10x concentrated Strep-Tactin® elution buffer. The contained desthiobiotin is a modified form of biotin that displaces Strep-tag®II and Twin-Strep-tag® fusion proteins from the engineered biotin-binding pocket of Strep-Tactin® in a competitive manner, resulting in a mild elution. Please note that Buffer E (10x) is not applicable for elution from Strep-Tactin®XT resins. Buffer R (10x) is a 10x concentrated Strep-Tactin® regeneration buffer containing HABA. HABA (2-[4'-hydroxy-benzeneazo]benzoic acid) displaces desthiobiotin from the modified biotin-binding pocket of Strep-Tactin® after the elution of Strep-tag®II or Twin-Strep-tag® fusion proteins. The yellow buffer turns red upon binding of HABA to Strep-Tactin®, clearly indicating the regeneration process and activity status of the column.
Please note that the Strep-Tactin® Buffer Set is not applicable for Strep-Tactin®XT.