Protein aggregation and adsorption at the oil/water interface: Role of interaction energies in 3-D-lattice dynamic MC simulations

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Kai O. Leonhard1, John M. Prausnitz2, and Clayton J. Radke1. (1) Department of Chemical Engineering, University of California, 201 Gilman Hall, Berkeley, CA 94720-1462, (2) Department of Chemical Engineering, University of California, Berkeley, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
Amino acid/solvent energy interaction parameters determine bulk aqueous protein aggregation and oil/water adsorption. A broad range of protein behavior emerges with small changes in the solvent interaction energies in the employed 20-letter alphabet: from nonaggregating, to reversibly aggregating, or to irreversibly aggregating into crystals or amyloid fibrils. A similar wide variety of fascinating behaviors occurs at the oil/water interface, ranging from nonadsorbing to reversibly to irreversibly adsorbing with different degrees of aggregation at the interface and penetration into one or both phases. The interaction-parameter set is systematically explored and optimized for representing realistic behavior typical of many aqueous globular proteins (fast folding; nonaggregating in the bulk, but irreversibly adsorbing to and aggregating at the interface). The proposed model for 3D-lattice dynamic MC simulations is useful for calculating the qualitative behavior of proteins in bulk solvents and at fluid/fluid interfaces as a function of protein size and composition.