pH dependent competition between YZ and YD in photosystem II probed by illumination at 5 K
The photosystem II (PSII) reaction center contains two redox active tyrosines, YZ and YD, situated on the D1 and D2 proteins, respectively. By illumination at 5 K, oxidation of YZ in oxygen-evolving PSII can be observed as induction of the Split S1 EPR signal from YZ• in magnetic interaction with the CaMn4 cluster, whereas oxidation of YD can be observed as the formation of the free radical EPR si
