LAUSR

In this paper, the three-coupling modified nonlinear Schrödinger (MNLS) equation with variable-coefficients is used to describe the dynamics of soliton in alpha helical protein. This MNLS equation with variable-coefficients is firstly transformed to the MNLS equation with constant-coefficients by similarity transformation. And then the one-soliton and two-soliton solutions of the variable-coefficient-MNLS equation is obtained by solving the constant-coefficient-MNLS equation with Hirota method. The effects of different parameter conditions on the soliton solutions are also discussed in detail. The interaction between two solitons are also discussed. Our results are helpful to understand the soliton dynamics in alpha helical protein.