Figure 4.

Dependence of the t_lag for photoactivation (A) and maximal oxygen yield (B) of activated centers of CP47RC dimers (●) and apo-WOC-PSII membranes (□) on MnCl₂ concentration. CP47RC dimers were measured in buffer containing 80 mM CaCl₂, protein equivalent to 10 μM RCs, and 0.8 mM ferricyanide. Light conditions are as shown in Fig. 2. The t_lag and maximal oxygen evolution were determined as in Fig. 3. Bars = mean values ± SD of at least three independent measurements carried out by using two different sample preparations. The t_lag data for PSII membranes were fitted to two first-order processes in Mn²⁺ concentration (t_lag = a_i[Mn/RC] + b_i; i = 1, 2; lines I and II). The dashed line equals I-II.