Reaction diagram for chemomechanical conversion. The diagram depicts a motor that can exist in two states (State 1 and State 2). In the absence of an applied force, the conversion of State 1 to State 2 is favored. The rate of the conversion occurs as a diffusive passage across an energy barrier separating the two states: first into the Transition State corresponding to the barrier peak; and then into the final passage. This passage across the energy barrier corresponds to the physical movement in the system, the movement of the motor protein. When a mechanical force is applied to the system, work will be done when protein moves and the energy profile will be the sum of the profile with no applied force and the energy profile due just to the movement of the protein. (For simplicity, the figure is drawn assuming a linear mapping of the reaction coordinate unto the mechanical coordinate.) As a result, the free energy difference between States 1 and 2 will vary as a function of the applied force, as will the position of the Transition State relative to States 1 and 2 and the energy difference between the Transition State and States 1 and 2, which in turn will alter the rate of the State 1→State 2 conversion.