  We show that the kinetics of microribbon formation of amelogenin molecules is
well described by a combination of translational and rotational diffusion of a
simplified anisotropic bipolar model consisting of hydrophobic spherical
colloid particles and a point charge located on each particle surface. The
colloid particles interact via a standard depletion attraction while the point
charges interact through a screened Coulomb repulsion. We study the kinetics
via a Brownian dynamics simulation of both translational and rotational motions
and show that the anisotropy brought in by the charge dramatically affects the
kinetic pathway of cluster formation and our simple model captures the main
features of the experimental observations.
