Abstract
The inhibitory effects of formate on oxygen evolving PS II membranes as a function of formate concentrations and pH values were investigated by O2 evolution and EPR measurements. To investigate the inhibition of the donor side of formate-treated PS II, YZo decay kinetics were measured by time-resolved EPR. Different formate concentrations affect only light-induced intensities of YZo EPR signal, while the pH values affect both light-induced intensities and decay rates of YZo. Intensity is proportional to formate concentration and decay rate is faster on low pH side. At 260 K, t1/e value of YZo decay kinetics is about 10 s at pH 5.0 and about 20 s at pH 6.0, respectively.
