Figure 2.

Fraction of slow phase (A_slow)of k_AB⁽²⁾ as a function of the concentration of added ZnSO₄ (●) or CdSO₄ (■). The kinetics of Fig. 2 were decomposed into two components: ΔA^450nm(t) = A_fast exp(−k_fastt) + A_slow exp(−k_slowt), where k_fast = 1,200 s⁻¹ (the observed rate without the addition of the metal) and k_slow = 120 s⁻¹ or 60 s⁻¹ (the observed rate upon addition of high concentrations of ZnSO₄ or CdSO₄, respectively). The solid curve is a fit to a standard binding equation with K_D = 0.3 μM. Conditions were the same as in Fig. 1.