Study on efficiency of oriented immobilization of antibodies on the SPR sensor surface using Staphylococcal protein A or its recombinant analogue

Aim. Comparison of IgG-binding activity of Staphylococcal protein A (SPA) and recombinant SPA with specially introduced C-terminal cysteine residue (SPA-Cys) after their immobilization on a gold sensor surface of the surface plasmon resonance (SPR) spectrometer. Methods. SPA or SPA-Cys was immobilized on a gold sensor surface to form two variants of bioselective elements of biosensor. SPR spectrometry was used for detection of IgG-binding activity of the immobilized proteins. Results. The SPR sensor response to the immobilization of SPA was more than three times less than that to immobilization of SPA-Cys. SPA-Cys demonstrates also almost 4-fold advantage in the number of immobilized molecules. Moreover, the bioselective element based on SPA-Cys showed a much better capability of binding IgG than the bioselective element based on SPA. Conclusions. The study of the processes of immobilization of SPA or SPA-Cys on the sensor surface of SPR spectrometer, and the interactions of immobilized proteins with human IgG demonstrated obvious advantages of recombinant protein A.