Elliptic Davydov solitons in {\alpha}-helix protein chain with exciton-exciton and exciton-phonon couplings

Abstract

We consider the Davydov model of {\alpha}-helix protein chain with both exciton-exciton and excitonphonon couplings and investigate on the evolution of elliptic solitons. In the discrete regime of the adiabatic limit, we analytically and numerically show that modulational instability induces the self-localization of energy in the {\alpha}-helix protein chain. By incorporating the continuous limit approximations, various nonlinear periodic modes are traced; strongly suggesting that the energy of the ATP hydrolysis is locally distributed over the {\alpha}-helix protein chain. It is generally found that the exciton-exciton coupling induces the inhomogeneity in the protein chain, which greatly enhances energy localization that is physically manifested as nonlinear periodic modes. Results of numerical simulations clearly depicts the evolution of these nonlinear periodic modes in the highly discrete, nonlinear, and coupled system that governs the dynamics of {\alpha}-helix protein chain.