Energy Supply and Photon Emission by Solitons in Alpha-Helical Proteins

Abstract

We study the nonlinear mechanism of energy supply in alpha-helical proteins with three polypeptide spines bound by hydrogen bonds. Taking into account the electron-phonon interaction results in the self-trapping of excitations in localized soliton-like states. The important role of the helical symmetry of macromolecules is elucidated for the formation, stability, and dynamical properties of Davydov's solitons. It is shown that the soliton with the lowest energy has an inner structure with the many-hump envelope. The total probability of the excitation in the helix is characterized by interspine oscillations with the frequency of oscillations proportional to the soliton velocity. These oscillations of charged soliton lead to the electromagnetic radiation of characteristic frequencies. The radiative lifetime of a hybrid soliton is calculated and shown to exceed the lifetime of an excitation on an isolated peptide group by several orders of magnitude.

Keywords:

• Alpha-helical protein
• Electron-phonon interaction
• Electromagnetic radiation
• Soliton