Impact of Urea on Monoclonal Antibodies: Multiple Destabilization and Aggregation Effects for Therapeutic Immunoglobulin G Proteins

We performed nano differential scanning fluorimetry (nanoDSF) measurements of immunoglobulin G (IgG) in urea gradient solutions under thermal unfolding. Our results show that the denaturing effect of urea on individual IgG domains can be monitored via a linear mapping of thermal shift curves to the corresponding urea concentrations. Assignment of IgG domains to each thermal shift curve allows for a reliable differentiation of the underlying mechanisms. Further results show a decisive influence of salt-induced electrostatic screening effects. We are able to explain all findings by preferential binding mechanisms in combination with electrostatic effects. The results of our study shed more light on the complex interaction mechanisms between buffer solutions and complex proteins, which are important for improving the shelf life of protein therapeutic formulation.