Browsing by Author "Arellano Saab, Amir Alam"

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    Crystallographic and Biochemical Studies of a Streptavidin Mutant: the Structural Basis of Ligand Recognition and Conformational Changes
    (2016) Arellano Saab, Amir Alam; Ng, Kenneth; Wong, Sui-Lam; Moorhead, Gregory
    A variant of streptavidin, SAVSBPM32, was previously designed to incorporate mutations that weaken binding to biotin and introduce a cysteine at position 86. Streptavidin-binding peptides have also been re-designed to test the binding capabilities of SAVSBPM32. The primary goal of this project was to crystallize SAVSBPM32 and evaluate its interactions with biotin, a cysteine containing SBP-Tag and a cysteine containing a biotinylation tag (CPFB-2). The crystal structure of SAVSBPM32 in complex with biotin revealed for the first time that the loop bridging the third and fourth b-strands in SAVSBPM32 can adopt a closed or an open conformation. The crystal structure of SAVSBPM32 in complex with CPFB-2 reveals the novel structure of a biotinylated peptide bound to streptavidin while also forming a disulphide bond. These findings confirm key design principles and suggest approaches for further development.