Proton-Coupled Electron- Transfer Processes in Photosystem II Probed by Highly Resolved g-Anisotropy of Redox-Active Tyrosine YZ
Proton-Coupled Electron- Transfer Processes in Photosystem II Probed by Highly Resolved g-Anisotropy of Redox-Active Tyrosine YZ
复制标题
通过氧化还原活性酪氨酸 YZ 的高分辨率 g 各向异性探测光系统 II 中的质子耦合电子转移过程
DOI：
10.1021/ja2000566
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Yamauchi S
中科院分区：
文献类型：
--
作者：
Matsuoka H.;Shen J.-R;Kawamori A.;Nishiyama K.;Ohba Y.;Yamauchi S
氧化还原活性酪氨酸残基YZin光系统II(PSII)的氧化与质子转移到氢键的D1-His190残基相耦合。由于YZ与水氧化络合物的亲和性和氧化还原活性，因此认为YZ在PSII的水氧化过程中起着重要作用。我们研究了酪氨酸基YZ·的g-各向异性，以期深入了解贫锰PSII中YZ·质子耦合电子转移的机制。利用PSII单晶在W波段(94.9 GHz)的电子顺磁共振波谱可以很好地分辨各向异性。用密度泛函理论计算了YZ·酚醛C-−-O键上的gX组分。高分辨的g-各向异性表明，YZ在酪氨酸氧化时失去一个苯酚质子到D_1-His190，而D_1-H_(190)在还原时将相同的质子返回给Y_Z·。
The oxidation of a redox-active tyrosine residue YZin photosystem II (PSII) is coupled with proton transfer to a hydrogen-bonded D1-His190 residue. Because of the apparent proximity of YZto the water-oxidizing complex and its redox activity, it is believed that YZplays a significant role in water oxidation in PSII. We investigated theg-anisotropy of the tyrosine radical YZ•to provide insight into the mechanism of YZ•proton-coupled electron transfer in Mn-depleted PSII. The anisotropy was highly resolved by electron paramagnetic resonance spectroscopy at the W-band (94.9 GHz) using PSII single crystals. ThegX-component along the phenolic C−O bond of YZ•was calculated by density functional theory (DFT). It was concluded from the highly resolvedg-anisotropy that YZloses a phenol proton to D1-His190 upon tyrosine oxidation, and D1-His190 redonates the same proton back to YZ•upon reduction.