An Affinity Complex Titration Isotherm for Mechanistic Modeling in Protein A Chromatography

Area of Science:

• Biochemical Engineering
• Chromatography
• Protein Purification

Background:

• Protein A chromatography is crucial for monoclonal antibody (mAb) purification.
• Accurate mechanistic modeling requires robust isotherm descriptions.
• Existing models may not fully capture pH-dependent binding complexities.

Purpose of the Study:

• To derive a pH-dependent affinity complex titration isotherm for protein A chromatography.
• To facilitate accurate mechanistic modeling of mAb binding and elution.
• To provide a versatile model applicable to diverse chromatographic conditions.

Main Methods:

• Derivation of a pH-dependent isotherm based on binding stoichiometry and titration equilibria.
• Modification of the Langmuir isotherm incorporating apparent capacity and equilibrium constants.
• Estimation of model parameters from four elution experiments.

Main Results:

• The derived isotherm accurately predicts chromatograms across varied conditions (mAbs, resins, pH, residence times).
• Model parameters are transferable, enabling extrapolation to different scenarios.
• Demonstrated compatibility with a wide range of process parameters and column dimensions.

Conclusions:

• The pH-dependent isotherm provides a powerful tool for mechanistic modeling in protein A chromatography.
• The model enhances prediction accuracy and process understanding for mAb purification.
• This approach facilitates optimization and scale-up of chromatographic processes.