pH Dependence of the Donor Side Reactions in Ca2+-Depleted Photosystem II
We have studied how low pH affects the water-oxidizing complex in Photosystem II when depleted of the essential Ca2+ ion cofactor. For these samples, it was found that the EPR signal from the YZ radical decays faster at low pH than at high pH. At 20 C, YZ decays with biphasic kinetics. At pH 6.5, the fast phase encompasses about 65% of the amplitude and has a lifetime of ~0.8 s, while the slow pha
