TY - JOUR AB - The role of chloride on the S-state transition in spinach Photosystem II (PS II) particles was investigated by EPR spectroscopy at low temperature and the following results were obtained. (1) After excitation by continuous light at 200 K, chloride-depleted particles did not show the EPR multiline signal associated with the S2 state, but only showed the broad signal at g = 4.1. The S2 multiline signal was completely restored upon chloride repletion. (2) In the absence of chloride the S2 multiline signal was not induced by a single flash excitation at 0°C. However, upon addition of chloride after the flash the signal was developed in darkness. (3) The amplitude of the multiline S2 signal thus developed upon chloride addition after flash illumination did not show oscillations dependent upon flash number. These results indicate that the O2-evolving complex in chloride-depleted PS II membranes is able to store at least one oxidizing equivalent, a modified S2 state, which does not give rise to the multiline signal. Addition of chloride converts this oxidizing equivalent to the normal S2 state which gives rise to the multiline signal. The modified S2 state is more stable than the normal S2 state, showing decay kinetics about 20-times slower than those of the normal S2 state, and the formation of higher S states is blocked. © 1986. AU - Ono,T AU - Zimmermann,JL AU - Inoue,Y AU - Rutherford,AW DO - 10.1016/0005-2728(86)90125-8 EP - 201 PY - 1986/// SN - 0005-2728 SP - 193 TI - EPR evidence for a modified S-state transition in chloride-depleted Photosystem II T2 - BBA - Bioenergetics UR - http://dx.doi.org/10.1016/0005-2728(86)90125-8 VL - 851 ER -