Research on biomechanical model of muscle fiber based on four-state operating mechanism of molecular motors

Mechanism research of myosin molecular motor provides a new way to reveal the microscopic feature of muscle contraction and has become a hot focus in biomechanical fields. Regarding the complex conformation change and multiple chemical states in the working cycle of myosin molecular motors, a four-state model which is closer to the actual compared with the two-state model used previous is proposed based on the chemical kinetics method. The steady-state behavior is studied by calculating the probability distribution, the motor speed and the diffusion coefficient under steady-state conditions. At the same time, considering the lack of investigation between the contraction forces and running state in previous studies, the relationship between the contraction force (load), length and speed are discussed through simulation. The simulation results show the validity of the four states model to describe the operating mechanism of molecular motors in muscle fibers and benefits to the macro modeling of skeletal muscle which is composed of muscle fibers.