Solitons in alpha-helical proteins

Abstract

We investigate some aspects of the soliton dynamics in an alpha-helical protein macromolecule within the steric Davydov-Scott model. Our main objective is to elucidate the important role of the helical symmetry in the formation, stability and dynamical properties of Davydov's solitons in an alpha-helix. We show, analytically and numerically, that the corresponding system of nonlinear equations admits several types of stationary soliton solutions and that solitons which preserve helical symmetry are dynamically unstable: once formed, they decay rapidly when they propagate. On the other hand, the soliton which spontaneously breaks the local translational and helical symmetries possess the lowest energy and is a robust localized entity. We also demonstrate that this soliton is the result of an hybridization of the quasiparticle states from the two lowest degenerate bands and has an inner structure which can be described as a modulated multi-hump amplitude distribution of excitations on individual spines. The complex and composite structure of the soliton manifests itself distinctly when the soliton is moving and some interspine oscillations take place. Such a soliton structure and the interspine oscillations have previosly been observed numerically in [A.C. Scott, Phys.Rev. A 26 578 (1982)]. Here we argue that the solitons studied by A. Scott, are hybrid solitons and that the oscillations arise due to the helical symmetry of the system and result from the motion of the soliton along the $\alpha$-helix. The frequency of the interspine oscillations is shown to be proportional to the soliton velocity.

26 pages, 8 figures

Cited by in corpus (11)

• On the quantum dynamics of Davydov solitons in protein $\alpha$-helices
• Thermal stability of solitons in protein $\alpha$-helices
• Quantum tunneling of Davydov solitons through massive barriers
• Launching of Davydov solitons in protein $\alpha$-helix spines
• A generalised Davydov-Scott model for polarons in linear peptide chains
• Long-range donor-acceptor electron transport mediated by alpha-helices
• Quantum tunneling of three-spine solitons through excentric barriers
• Quanta of Local Conformational Change: Conformons in alpha-helical proteins
• Spontaneous Polaron Transport in Biopolymers
• On the vibron-polaron damping in quasi 1D macromolecular chains
• Quantum transport and utilization of free energy in protein $\alpha$-helices