An Eseem Study of the Tyrosyl Donor D in Photosystem II
An Eseem Study of the Tyrosyl Donor D in Photosystem II
复制标题
光系统II中酪氨酰供体D的Eseem研究
DOI：
10.1007/978-94-009-0511-5_110
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发表时间：
1990
影响因子：
1.4
通讯作者：
A. Hoff
中科院分区：
文献类型：
--
作者：
R. Evelo;S. Dikanov;A. Hoff
植物光合作用中的放氧发生在高等植物和藻类的放氧光系统II（PS II）的供体侧[1]。H2O的氧化和伴随的氧释放发生在析氧复合物（OEC）中。在OEC附近，电子供体D是局部化的。最近，D被鉴定为PS II反应中心D2蛋白亚基上的酪氨酸160 [2]。D氧化成稳定的酪氨酸自由基D产生众所周知的EPR信号，即所谓的信号II（S II）。酪氨酸形成两种可能的氧化产物：一种是质子化阳离子，其特征在于g值为2.0033和超精细（hf）分裂，其与参考文献[3]中通过简单休克尔理论得出的游离酪氨酸的自旋密度分布非常一致。另一个是中性的，可能是氢键结合的酪氨酸自由基，g值为2.0049，自旋密度分布见参考文献[3，4]。
Oxygen evolution in plant photosynthesis takes place at the donor side of the oxygen-evolving photosystem II (PS II) of higher plants and algae [1]. The oxidation of H2O and the concomitant release of oxygen occurs in the Oxygen Evolving Complex (OEC). Near the OEC the electron donor D is localized. Recently D was identified as a tyrosine 160 on the D2 protein subunit of the PS II reaction center [2]. The oxidation of D to a stable tyrosine radical D gives rise to a well known EPR signal, the so-called Signal II (S II). Tyrosine forms two possible oxidation products: one is a protonated cation, characterized by a g-value of 2.0033 and hyperfine (hf) splittings that agree well with the spin density distribution by simple Huckel theory in ref [3] for free tyrosine. The other is a neutral, possibly hydrogen-bonded tyrosine radical with a g-value of 2.0049 and a spin density distribution given in refs [3,4].