Recombinant Staphylococcal protein A with cysteine residue for preparation of affinity chromatography stationary phase and immunosensor applications

Aim. Engineering of recombinant Staphylococcal protein A with cysteine residue (SPA-Cys) for preparation of affi nity chromatography stationary phase and formation of bioselective element of immunosensor. Methods. DNA sequences encoding IgG-binding region of SPA, His-tag and cysteine were genetically fused and expressed in E. coli. SPA-Cys was immobilized on maleimide-functionalized silica beads for affi nity chromatography stationary phase preparation and on a gold sensor surface as a bioselective element of immunosensor. Results. SPA-Cys was expressed at a high-level in a soluble form. The target protein was purifi ed and showed a high IgG-binding activity. The capacity of the obtained SPA-Cys-based affi nity chromatography stationary phase was 10-12 mg of IgG /ml. The purity of eluted IgG was more than 95 % in one-step purifi cation procedure. The developed SPA-Cys-based bioselective element of immunosensor selectively interacted with human IgG and did not interact with the control proteins. Conclusions. The recombinant Staphylococcal protein A with cysteine residue was successfully used for the preparation of affi nity chromatography stationary phase and formation of the bioselective element of immunosensor.