Avidin - Model 2-0204-050 -Biotin and Biotinlyated Proteins

Avidin is a tetrameric biotin binding protein (KD ~1 x 10^-14) extracted from egg white. It prevents biotin and biotinylated proteins from binding to Strep-Tactin  or Strep-Tactin XT, whereas binding of the Twin-Strep-tag and Strep-tagII is not influenced. Biotin and/or biotinylated proteins can potentially reduce the binding capacity of Strep-Tactin as well as Strep-Tactin XT and are present in cell lysates and cell culture media, especially from mammalian or insect cells. Thus, if Twin-Strep-tag and Strep-tag II fusion proteins from biotin-containing extracts or media are intended to be purified via Strep-Tactin or Strep-Tactin XT affinity chromatography, biotin has to be masked by addition of avidin prior to application onto the resin. Biotin Blocking Buffer (2-0501-002) for western blotting can be prepared by dissolving 2.5 mg/ml Avidin in PBS buffer.