Abstract
To understand the mechanism underlying the one-dimensional (1D) Brownian motion of proteins, we analyzed the behaviors of counterions along microtubules using the electroorientation method and compared these with the 1D Brownian motion of charged nanoparticles. Both results demonstrated that during 1D Brownian motion, each positively charged nanoparticle behaves as a polycation constrained within the electrostatic field around the microtubules. Owing to the polyelectrolytic nature of microtubules, nanoparticles can move along microtubules with a diffusion constant independent of the charge density of the microtubules. The study highlights the possibility that 1D Brownian motion of proteins is based on a similar, nonspecific charge-dependent mechanism.
