The strong interaction between streptavidin and biotin is one of the most commonly exploited tools in chemistry and biology. Methods for the facile derivatization of a variety of molecules (in particular, proteins) with biotin have been introduced, in order to allow their efficient recovery, immobilization and detection with streptavidin-based reagents. However, when desired, the release of biotinylated proteins from the streptavidin-based reagents remains a major problem, due to the extraordinary stability of this complex. This chapter presents a protocol developed in our laboratory for the quantitative elution of biotinylated proteins from streptavidin sepharose, featuring harsh elution conditions and competition with free biotin. The usefulness of the method is shown by the recovery of biotinylated proteins from organ homogenates, obtained from mice perfused with a reactive ester derivative of biotin.
