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首页> 外文期刊>Chemical Reviews >Mn4Ca Cluster in Photosynthesis: Where and How Water is Oxidized to Dioxygen
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Mn4Ca Cluster in Photosynthesis: Where and How Water is Oxidized to Dioxygen

机译：Mn4Ca团簇在光合作用中：水在哪里以及如何被氧化成双氧

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Oxygen, which supports all aerobic life, is produced by photosynthetic water oxidation in plants, algae, and cyanobacteria. The water-oxidation reaction probably first appeared in nature ~3 billion years ago in the precursors to present-day cyanobacteria, although the exact timing is not yet entirely clear.~(1-5) A key component in the appearance of oxygenic photosynthesis was a metal complex that could store oxidizing equivalents to facilitate the four-electron oxidation of two water molecules to dioxygen, meanwhile making the electrons available for the reductive carbon-fixing reactions required for sustaining life.~(6-8) This metal complex involved in oxygenic photosynthesis, the oxygen-evolving complex (OEC), consists of an oxo-bridged structure with four Mn atoms and one Ca atom. No variations have been observed so far among oxygenic photosynthetic organisms through higher plants and algae back to cyanobacteria, which represents the earliest oxygenic photosynthetic organisms. Oxygen itself is the byproduct of the photosynthetic water oxidation reaction shown in eq 1: 2H_2O→O_2+4H~++4e~- (1) However, it was this oxygen that enabled oxygenic life to evolve and that led to the current diverse and complex life on earth by dramatically increasing the metabolic energy that became available from aerobic respiration. Oxygen produced by this process was also key for the development of the protective ozone layer, which allowed life to transition from marine forms to terrestrial life.
机译：氧气通过植物，藻类和蓝细菌中的光合作用水氧化产生，从而维持所有有氧生活。水氧化反应可能是在大约30亿年前于当今蓝细菌的前体中首次出现在自然界中，尽管确切的时机尚未完全清楚。（1-5）氧光合作用出现的关键因素是一种金属配合物，可以存储氧化当量以促进两个水分子的四电子氧化为双氧，同时使电子可用于维持生命所需的还原性固碳反应。〜（6-8）氧气的光合作用是一种放氧复合物（OEC），由具有四个Mn原子和一个Ca原子的氧桥结构组成。迄今为止，尚未通过高等植物和藻类返回到蓝细菌而在含氧光合生物中观察到变化，这代表了最早的含氧光合生物。氧气本身是光合水氧化反应的副产物，如式1所示：2H_2O→O_2 + 4H〜++ 4e〜-（1）然而，正是这种氧气使氧气的生命得以发展，并导致了电流的多样化和通过显着增加有氧呼吸所能提供的代谢能量，使地球上的生命变得复杂。该过程产生的氧气对于保护性臭氧层的发展也至关重要，该保护性臭氧层使生命从海洋形态过渡到陆地生命。

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