Fig. 5.

ATP hydrolysis data fits. Presteady-state, quench-flow measurements of the time course of ATP hydrolysis by rapidly mixing MoFe protein (10 μM) and Fe protein (40 μM) with [α-³²P]ATP (2 mM) (●). Dashed black line: half-sites model, Scheme B, using rate constants, k_ET = 140 s⁻¹, k_ATP = 36 s⁻¹, k_Pi = 16 s⁻¹, and k_off = 11.9 s⁻¹, as derived from the phenomenological fits to the experimental data, along with the recharging model. Solid black line: independent-sites model, Scheme A, calculated analogously. Red line: calculated from the rate parameters obtained by the global fit to negative cooperativity Scheme C, as given in the scheme. (Inset) Data and simulations to longer times.