Production of Recombinant Streptavidin and Optimization of Refolding Conditions for Recovery of Biological Activity

Background: Streptavidin is a protein produced by Streptomyces avidinii with strong biotin-binding ability. The non-covalent, yet strong bond between these two molecules has made it a preferable option in biological detection systems. Due to its extensive use, considerable attention is focused on streptavidin production by recombinant methods. Methods: In this study, streptavidin was expressed in Escherichia coli (E. coli) BL21 (DE3) pLysS cells and purified by affinity chromatography. Various dialysis methods were employed to enable the protein to refold to its natural form and create a strong bond with biotin. Results: Streptavidin was efficiently expressed in E. coli. Streptavidin attained its natural form during the dialysis phase and the refolded protein bound biotin. The addition of proline or arginine to the dialysis buffer resulted in a refolded streptavidin with greater affinity for biotin than refolding in dialysis buffer with no added amino acids. Conclusions: Dialysis of recombinant streptavidin in the presence of arginine or proline resulted in proper refolding of the protein. The recombinant dialyzed streptavidin bound biotin with affinity as great as that of a commercial streptavidin.