Evaluation of Binding Kinetics and Thermodynamics of Antibody–Antigen Interactions and Interactions Involving Complement Proteins

The study of kinetics and thermodynamics of protein–protein interactions can contribute to assessment of the mechanism of molecular recognition process. These analyses can provide information about conformational changes and noncovalent forces that influence the initial recognition between proteins and stabilization of the complex. Studying these aspects may lead to a better comprehension of functions of proteins in biological environment and can become useful for the rational modification of some interactions by engineering of one of the implicated partners. Real-time biosensor assays based on surface plasmon resonance have been widely applied for the label-free evaluation of protein–protein interactions, allowing their characterization in term of binding affinity and kinetics. In the present chapter, we provide a protocol for the assessment of interactions involving complement proteins or antibodies, the protagonists of the immune system. We reported guidelines and indications concerning the analysis of the experimental data for the estimation of the kinetic parameters and for the evaluation of activation and equilibrium binding thermodynamics.