Redox potential of pheophytin a in photosystem II of two cyanobacteria having the different special pair chlorophylls
Redox potential of pheophytin a in photosystem II of two cyanobacteria having the different special pair chlorophylls
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DOI：
10.1073/pnas.0913460107
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发表时间：
2010-02-23
影响因子：
11.1
通讯作者：
Mimuro, Mamoru
中科院分区：
文献类型：
--
作者：
Allakhverdiev, Suleyman I.;Tomo, Tatsuya;Mimuro, Mamoru
在氧光合生物中，光系统（PS） II对水的氧化是地球上能量的主要来源，导致一种稳定的还原剂的产生。水氧化产生高氧化电位的机制一直是光合作用研究的重点。这个电位没有直接估计，而是通过初级电子受体，叶绿素（Phe）a的氧化还原电位来测量的。然而，Phe a的报告值仍然存在争议。这里,我们测量了氧化还原电位的板式换热器在生理条件下(pH值7.0;25摄氏度)在两个蓝藻不同特殊对叶绿素(背影):集胞藻属sp PCC。6803年,他特别对PS II包括的背影,Acaryochloris滨MBIC 11017,特别对PS II背影d。我们获得了氧化还原电位由-536 + / - 8集胞藻属sp的mV。6803年和-478年PCC + / - 24 mV a滨PS II复合物在1.0甜菜碱的存在。聚囊藻（Synechocystis sp. PCC 6803 (P680)）和a . marina （P713）的特殊PS II对电位分别为1.20 V和1.18 V，两者间Phe a氧化还原电位的差异与Chl a和Chl d吸收光能的差异密切相关。这清楚地表明，在含氧光合生物中，无论特殊对叶绿素如何，水氧化系统的特性都是守恒的。
Water oxidation by photosystem (PS) II in oxygenic photosynthetic organisms is a major source of energy on the earth, leading to the production of a stable reductant. Mechanisms generating a high oxidation potential for water oxidation have been a major focus of photosynthesis research. This potential has not been estimated directly but has been measured by the redox potential of the primary electron acceptor, pheophytin (Phe)a. However, the reported values for Phe a are still controversial. Here, we measured the redox potential of Phe a under physiological conditions (pH 7.0; 25 degrees C) in two cyanobacteria with different special pair chlorophylls (Chls): Synechocystis sp. PCC 6803, whose special pair for PS II consists of Chl a, and Acaryochloris marina MBIC 11017, whose special pair for PS II consists of Chl d. We obtained redox potentials of -536 +/- 8 mV for Synechocystis sp. PCC 6803 and -478 +/- 24 mV for A. marina on PS II complexes in the presence of 1.0 M betaine. The difference in the redox potential of Phe a between the two species closely corresponded with the difference in the light energy absorbed by Chl a versus Chl d. We estimated the potentials of the special pair of PS II to be 1.20 V and 1.18 V for Synechocystis sp. PCC 6803 (P680) and A. marina (P713), respectively. This clearly indicates conservation in the properties of water-oxidation systems in oxygenic photosynthetic organisms, irrespective of the special-pair chlorophylls.