Bubble Formation in Helicoidal DNA Molecules

Wave interaction is addressed the framework of the helicoidal Peyrard-Bishop model of DNA. The model is first reduced to a set of coupled nonlinear Schrodinger equations via the multiple scale expansion. Modulational instability analysis shows that multi-breather trains exist in large regions of instability, while trains of one-humped breathers are observed for the single excitation mode. Analytical solutions are proposed, where single modes are proposed to described DNA respiration and coupled waves rather describe the bubbles observed in experiments. These bubbles are shown to be more effective under weak helicoidal coupling. The process of strand separation is also discussed. PACS number(s): 87.14.E-, 87.15.H-, 05.45.Yv, 05.45.-a