FIGURE 3.

Temperature dependence of the parameters characterizing the hydrolysis activity at 2 mM MgATP. (a) The initial (A_init) and steady-state (A_ss) activities are indicated by triangles and inverted triangles, respectively. The steady-state values obtained with the thermophilic regeneration system (gray squares) are likely underestimated. The fraction of active F₁ at steady state (R_act = A_ss/A_init) is indicated by black diamonds. (Dashed line) Average of R_act between 4 and 30°C; T, absolute temperature. (b) The black line represents the apparent rate constant, k_app, for the relaxation from the initial high-activity state to the steady state, and indicates an activation energy of 120 kJ K⁻¹ mol⁻¹. Green and orange lines indicate the rate constants for the conversion from active to inactive (k_inact) and from inactive to active (k_act) states, respectively, with activation energies of 119 kJ K⁻¹ mol⁻¹ and 126 kJ K⁻¹ mol⁻¹ for k_inact and k_act, respectively.