Figure 4.

Comparison of stepping and ATP hydrolysis rates. Stepping rate (3× rotation rate) was determined for each spot as 1/<t> or 3/<3t>, where <t> and <3t> are average times per step (i, green triangles) or turn (ii, red triangles), respectively. Larger symbols show averages over spots. Black circles show previous estimates with actin (20). Hydrolysis rate V (blue diamonds with error bars showing SD) was estimated in solution (i.e., the rate shown is the ensemble average over all molecules in the solution) and was fitted with V = (k_cat^aK_m^b[ATP] + k_cat^b[ATP]²)/([ATP]² + K_m^b[ATP] + K_m^aK_m^b), where k_cat^a = 83 s⁻¹, k_cat^b = 292 s⁻¹, K_m^a = 6.3 μM, and K_m^b = 680 μM. Hydrolysis rate of Cy3-labeled F₁ (not shown) agreed within experimental error.