Soliton Excitations in Alpha-Helical Protein Structures

We propose a general theory for soliton excitations in alpha-helical protein structures. In this framework, the interaction between peptide groups is separated into the Amide I exciton-phonon coupling effect and the effect of anharmonicity of phonon. In most of previous theories, only one of the two effects has been taken into account. Expressions for both effects are taken so that they coincide with the previous theoretical results in limiting cases. In the general case we show that both effects should be taken into account.