In this work, a phenomenological model for protein adsorption incorporating charge regulation is developed that is based on principles of classical thermodynamics. It is shown that this adsorption model includes as a subcase a charge regulation protein adsorption model developed previously that is based on statistical mechanical perturbation theory. However, the phenomenological model developed here extends these previous adsorption models into several new areas, including to the case of mixed-mode chromatography. To test the model and assess its suitability for correlating adsorption data, ion-exchange (IEX) and mixed-mode (MM) chromatography experiments were used to study the adsorption mechanism for the interaction between proteins and IEX/MM packings. Column experiments using both anion exchange and mixed-mode packings were conducted under different operating conditions of pH and ionic strength. Linear adsorption constants for the protein-column packing interactions were calculated using the measured chromatographic retention times under the different employed conditions. Experimental data were fitted to models to enable prediction of the amount of protein adsorbed and hence elucidate the underlying mechanism of adsorption. To gain further insights into the adsorption mechanism, Monte Carlo Docking simulations were also performed. This work is important in developing computer-aided design methodologies for optimized protein purification.

Experimental and theoretical studies of protein adsorption onto ion exchange and mixed mode chromatographic column packings

255th National Meeting (2018)

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