title: Phase diagram of a model of the protein amelogenin.
abstract: There has been considerable recent interest in the self-assembly and phase behavior of models of colloidal and protein particles with anisotropic interactions. One example of particular interest is amelogenin, an important protein involved in the formation of dental enamel. Amelogenin is primarily hydrophobic with a 25-residue charged C-terminus tail. This protein undergoes a hierarchical assembly process that is crucial to mineral deposition, and experimental work has demonstrated that the deletion of the C-terminus tail prevents this self-assembly. A simplified model of amelogenin has been proposed in which the protein is treated as a hydrophobic sphere, interacting via the Asakura-Oosawa (AO) potential, with a tethered point charge on its surface. In this paper, we examine the effect of the Coulomb interaction between the point charges in altering the phase diagram of the AO model. For the parameter case specific to amelogenin, we find that the previous in vitro experimental and model conditions correspond to the system being near the low-density edge of the metastable region of the phase diagram. Our study illustrates more generally the importance of understanding the phase diagram for proteins, in that the kinetic pathway for self-assembly and the resulting aggregate morphology depends on the location of the initial state in the phase diagram.
authors: Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
authors: Jason
authors: J
authors: Haaga
authors: Drew University, Madison, New Jersey 07940, USA.
authors: Elizabeth
authors: E
authors: Pemberton
authors: Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
authors: J D
authors: JD
authors: Gunton
authors: Department of Materials Science, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
authors: J M
authors: JM
authors: Rickman
mesh_terms: D000465:Algorithms; D053523:Amelogenin / Q000737:chemistry*; D003198:Computer Simulation; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D009010:Monte Carlo Method; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000737:chemistry
chemical_list: D053523:Amelogenin; D011092:Polyethylene Glycols