Effect of twisting on the behavior of a double-stranded polymer chain: A Monte Carlo simulation

DNA and some proteins have a multistranded chain structure and exhibit characteristic tertiary structures due to twisting or anisotropic rigidity. We studied the effect of chain twisting on the behavior of a circular double-stranded polymer chain using a Monte Carlo simulation with bond fluctuation model. We found that there are two regimes for the chain conformation, depending on its twisting. In the first regime, with weak twisting, a circular chain behaves like a coiled linear chain. In the second regime, the chain shows scaling dependencies characterized by supercoiled structures.