Development of a tetrameric streptavidin mutein with reversible biotin binding capability: engineering a mobile loop as an exit door for biotin. oleh Valerie J O'Sullivan, Isabelle Barrette-Ng, Eric Hommema, Greg T Hermanson, Mark Schofield, Sau-Ching Wu, Claudia Honetschlaeger, Kenneth K-S Ng, Sui-Lam Wong