中文摘要：

在绿色植物放氧光合作用中,光系统II（PSII）催化着自然界利用光能将水裂解并释放出氧气的化学反应.在研究PSII的生物催化机理中,电子顺磁共振（EPR）波谱学发挥着非常重要的作用.该文综述了与水裂解有关的EPR应用研究,如锰簇Mn4O5Ca的不同氧化中间态,以及这些不同氧化态的锰簇与酪氨酸YZ自由基的磁性相互作用等,这些进展揭示了水裂解过程是一个逐步的与质子耦联的电子传递过程.

英文摘要：

In oxygenic photosynthesis,photosystem II（PSII） catalyzes the water splitting/oxidation and O2 release into the ambient atmosphere upon light absorption.The catalytic active site therein is an inorganic cluster consisted of 4 Mn,1 Ca and 5 O.Electron paramagnetic resonance（EPR） spectroscopy plays a key role in the endeavor to elucidate the mechanism of water splitting.In this short review,we emphasized the interpretation of EPR spectra originating from different oxidized Mn4O5Ca clusters and from different magnetic interactions between the Mn4O5Ca cluster and a nearby tyrosine radical,combined with the methanol effects.The overall oxidation of two substrate water molecules is a stepwise and proton-coupled electron transfer.