Strep-tag® Protein Purification-Strep-tactin Columns, Resins and Related Reagents

The purification of Strep-tag II fusion proteins is very simple and user-friendly. The complete procedure can be performed under nearly physiological conditions, e.g. in PBS buffer and 2.5 mM desthiobiotin in PBS buffer during elution.

• Once the tagged protein has bound specifically to the column the unspecific proteins are rapidly washed away with small amounts of physiological washing buffer.
• Then, small amounts of the specific competitor desthiobiotin are added in order to elute the Strep-tag protein. Since the buffer conditions during elution essentially remain unchanged, potentially unspecifically binding proteins (without Strep-tag) will not be eluted and, thus, will not contaminate the protein of interest.
• To regenerate the column desthiobiotin is displaced by adding the yellow solution HABA (hydroxyazophenyl benzoic acid). After the removal of desthiobiotin the column turns red due to the binding of HABA as red colored hydrazone isomer to Strep-Tactin. This clear color change indicates the regeneration and activity status of the column.
• HABA can be removed simply by using washing buffer. Once the red color has disappeared the column can be re-used.