Figure 8.

Hypothetical kinetic model describing the experimental data. Switching between different energy landscapes may explain different velocity modes and different timescales of switching. (a) Free energy of depolymerized state is energetically lower than polymerized state. Thus, the retraction rate k₋ is higher than the elongation rate k₊. (b) With increasing external force, the free energy of the polymerized state decreases compared to the depolymerized state. The switching rate k between the landscapes depends on force. (c) The high velocity mode may be described by an energy landscape in which the free energy difference between polymerized and the depolymerized states increases compared to a.