Comparative studies of the S-0 and S-2 multiline electron paramagnetic resonance signals from the manganese cluster in Photosystem II

Electron paramagnetic resonance (EPR) spectroscopy is one of the major tech niques used to analyse the structure and function of the water oxidising co mplex (WOC) in Photosystem II. The discovery of an EPR signal from the S-0 state has opened the way for new experiments, aiming to characterise the S- 0 state and elucidate the differences between the different S states. We pr esent a review of the biochemical and biophysical characterisation of the S -0 state multiline signal that has evolved since its discovery, and compare these results to previous and recent data from the S-2 multiline signal. W e also present some new data from the S-2 state reached on the second turno ver of the enzyme. (C) 2001 Elsevier Science B.V. All rights reserved.