The kinetic study on the interactions of IgG and antibody-binding proteins based on SPR sensor.

We study the interactions between staphylococal protein A or streptococcus protein G and immunoglobulin IgG, respectively, based on the self-developed wavelength-based surface plasmon resonance (SPR) sensing system combined with the kinetic analysis. The experimental results show that the association rate constants k_a of protein A and protein G with IgG are 1. 3 X 105 L⋅mol^-1⋅s^-1 and 5. 0 X 10⁴ L⋅mol^-1⋅s^-1, indicating that the protein A binds to IgG more efficiently. At the same time, the dissociation rate constants k_d of protein A and protein G from IgG are detected to be 2. 1 x 10 ^-2 s^-1 and 5. 0 x 10 ^-3 s^-1, indicating that the complex formed by protein G and IgG is more stable. In addition, the ratio of k_d to k_a indicates that protein G has higher affinity for IgG. This study may provide necessary reference and important theoretical support for the optimization of antibody immobilization methods. [ABSTRACT FROM AUTHOR]