Protein Selectivity In Multimodal Chromatography

A series of simulations and experiments have been carried out to examine the relevant interactions in multimodal chromatographic systems. Molecular dynamics protein-ligand simulations were performed to determine multimodal ligand binding sites on the protein surface. These simulations were found to corroborate experimental data obtained with both NMR and chromatography experiments for a library of homologous protein mutants. Further, these MD simulations were conducted with a combinatorial ligand library to study the role of synergy in the determination of ligand binding sites for these “pseudo-affinity” ligands. All-atom MD simulations were also performed to examine the binding of several proteins to self-assembled monolayers presenting relevant multimodal ligands. Protein adsorption behavior in the presence of various mobile phase modifiers at varying salt concentrations was examined to identify unique selectivity windows and to elucidate the effect of these modifiers on the intermolecular interactions in these systems. Simulations were also carried out with model systems in the presence of these modifiers to evaluate several key hypotheses related to synergistic interactions in these multimodal systems. Finally, novel molecular descriptors based on the molecular simulations were developed and employed to facilitate methods development in these MM systems.