Figure 7.

ATP-induced dissociation of ^BMS1-actin in the presence of ADP. (a) Pyrene fluorescence changes observed on mixing 16 mM MgATP with 1 μM ^BMS1-actin in the presence of 150 μM ADP at 20 °C. The best-fit double exponential is superimposed with k_obs = 94 s⁻¹ (ΔF+55%) and 9.6 s⁻¹ (ΔF +10%) for the fast and slow phase, respectively. (b) Temperature dependence of ATP-induced dissociation of ^BMS1-actin in the presence of ADP with k_obs (fast (▪) and slow (•) phase) as a function of temperature. From the slope the activation energy can be calculated. E_a = 106 kJmol⁻¹ and 98 kJmol⁻¹ for the fast and the slow phase, respectively.