Figure 6.

Rate constants for the intermediate phases, k_obs,2, for reduction of WT*K79H by Co(terpy)₂²⁺ as a function of Co(terpy)₂²⁺ concentration at different pH values. (A) k_obs,2 versus Co(terpy)₂²⁺ concentration data at pH 5.5 showing fits to eq 2 (dashed curve) and eq 4 (solid curve). (B) k_obs,2 versus Co(terpy)₂²⁺ concentration data from pH 5 to 8 fit to eq 4. The values of k_ET used in these fits were derived from fits of the data in Figure 5B and Figure S1 in the Supporting Information to a linear equation. The rate constants k_ET(alk), k_b and k_f in the square-scheme kinetic model (Figure 3), derived from the fits to eq 4, are collected in Table 1.