The small Strep-tag II (WSHPQFEK) can be used to purify active, native conformation proteins to high purity on Strep-Tactin resins. In addition, it can be used in combination with the His tag in a standardized two-step purification procedure. Strep-Tactin is available as Superflow chromatography resin for larger scale purification (up to 9 mg/ml resin). Strep-Tactin resin is also available in prefilled cartridges for automated purification on liquid chromatography systems.