Molecular Dynamics Simulations of a Binary Protein Mixture Adsorption onto Ion-Exchange Adsorbent

Abstract

Molecular dynamics (MD) simulations with a coarse-grained model are applied to investigate the binary adsorption of proteins onto an ion-exchange chromatographic medium. In particular, the adsorption of human serum albumin (HSA) and bovine hemoglobin (bHb) on the anion exchanger Q Sepharose FF is studied. Simulations with different initial orientations of the proteins and different protein–protein distances are carried out over a 2000 ns time scale. The protein–ligand potential energies and protein–ligand minimum distances are analyzed, and stable adsorption of HSA but no stable adsorption of bHb is observed. Interactions between HSA and bHb as well as a coupled movement of these two proteins are observed in all simulations. Because of the interaction between these two proteins, their rotations and adjustments to reach a favorable adsorption configuration are hindered. The competition is further indicated by changing adsorption sites on the HSA surface. The interaction and aggregation of the two proteins ...