Figure 4. Dependence of the stepping kinetics on the concentrations of ATP and ATP-γ-S.

(A) The pause duration after the first, 7-bp compound step (t_p,7) at various ATP-γ-S concentrations and 2 μM ATP.

(B) The pause duration between each 1-bp elementary step (t_p) at various ATP-γ-S concentrations and 2 μM ATP. All pauses except for the ones after 6, 7, and 8 bp of translocation were pooled to determine t_p. As shown in Figure S4, in addition to the 7^th pause, the 6^th and 8^th pauses also appear longer than the remaining ones, likely due to errors in pause identification. The value of t_p at 0 μM ATP-γ-S was derived from 1 / k value obtained from the Γ-distribution in Figure 3B.

(C) Dependence of t_p on the ATP concentration at 2 mM ATP-γ-S. At this saturating concentration of ATP-γ-S, all pauses, including the 7^th one, had approximately equal durations and were pooled to determine t_p.

All data are shown as the mean ± SEM (N = 15 - 100 events).

See also Figure S4.