Orientation of monoclonal antibodies in ion-exchange chromatography: A predictive quantitative structure-activity relationship modeling approach

- mAb binding orientation in ion-exchange chromatography is determined in silico.
- mAb orientation is found to be varying depending on Fab fragment composition.
- Electrostatic potential and hydrophilicity properties contribute to binding strength and orientation.
- mAb binding orientation is influenced by liquid phase ionic strength.
- Predictive QSAR model for IEX chromatography for mAb and model proteins established.

Chromatographic separation of biopharmaceuticals in general and monoclonal antibodies (mAbs) specifically is the bottleneck in terms of cost and throughput in preparative purification. Still, generalized platform processes are used, neglecting molecule specific characteristics, defining protein-resin interaction terms. Currently used in silico modeling approaches do not consider the orientation of the molecule towards the chromatographic resins as a result of the structural features on an atomic level. This paper describes a quantitative structure-activity relationship (QSAR) approach to model the orientation of mAbs on ion exchange chromatographic matrices as a function of property distribution and mobile phase characteristics. 6 mAbs were used to build a predictive QSAR model and to investigate the preferred binding orientations and resulting surface shielding on resins. Thereby different dominating orientations, caused by composition of Fab fragments of the mAbs, could be identified. The presented methodology is suitable to gain extended insight in molecule orientation on chromatographic resins and to tailor purification strategies based on molecule structure.