Comparative studies of the S0 and S2 multiline electron paramagnetic resonance signals from the manganese cluster in Photosystem II

Abstract

Electron paramagnetic resonance (EPR) spectroscopy is one of the major techniques used to analyse the structure and function of the water oxidising complex (WOC) in Photosystem II. The discovery of an EPR signal from the S0 state has opened the way for new experiments, aiming to characterise the S0 state and elucidate the differences between the different S states. We present a review of the biochemical and biophysical characterisation of the S0 state multiline signal that has evolved since its discovery, and compare these results to previous and recent data from the S2 multiline signal. We also present some new data from the S2 state reached on the second turnover of the enzyme.

Ammonia displaces methanol bound to the water oxidizing complex of photosystem II in the S2 state

“…In order to study the binding of ammonia and methanol to the WOC, it is important to study the S 2 state. Although methanol appears to bind in the lower S states [3,4,8,9], ammonia binding occurs in S 2 [13–18]. Therefore, we used dark adapted PSII samples in the S 1 state, illuminated them at 200 K to reach the S 2 state and then annealed the samples at 273 K for ∼1 min to ensure binding to S 2 and loss of interfering signals from the iron‐semiquinone form of the electron acceptor Q A , [22].…”

“…Efficient function of the water oxidising enzyme requires the inorganic cofactors calcium and chloride. The S 0 [3,4] and S 2 [5] states have complex multiline electron paramagnetic resonance spectrometry (EPR) spectra detectable in standard perpendicular mode EPR.…”

The manganese complex of photosystem II in its reaction cycle—Basic framework and possible realization at the atomic level

“…Results obtained by XAS [40][41][42][43][44][45][46], FTIR [47][48][49][50][51], EPR [52][53][54][55][56][57][58], mass spectroscopy [57,59,60], and computational methods [61][62][63] eventually may provide the complementary information needed to construct a complete atomic-resolution model that includes not only the metal ion, bridging oxides and ligating residues, but also the location of water molecules, protons and oxidizing equivalents. The above and other spectroscopic techniques (see Section 2.3 and, e.g.…”

Time-resolved X-ray spectroscopy leads to an extension of the classical S-state cycle model of photosynthetic oxygen evolution

“…Results obtained by X-ray absorption spectroscopy (XAS) (for review see Penner-Hahn 1999a; Dau et al 2001Robblee et al 2001), FTIR (Chu et al 2001;Debus 2001;Yamanari et al 2004;Berthomieu and Hienerwadel 2005), and EPR (Geijer et al 2001;Peloquin and Britt 2001;Carrell et al 2002;Britt et al 2004) may provide the complementary information which is needed for a complete model which includes the location of water molecules, protons, and oxidation equivalents. The above and other spectroscopic techniques eventually also may provide the needed insight in the reaction dynamics, i.e., the structural changes associated with advancement in the reaction cycle.…”