A metalloradical mechanism for the generation of oxygen from water in photosynthesis
A metalloradical mechanism for the generation of oxygen from water in photosynthesis
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DOI：
10.1126/science.277.5334.1953
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发表时间：
1997-09-26
期刊：
影响因子：
56.9
通讯作者：
Babcock, GT
中科院分区：
文献类型：
--
作者：
Hoganson, CW;Babcock, GT
在植物和藻类中，光系统II利用光能将水氧化成氧，在一个金属自由基位点，该位点包括一个四核锰簇和一个酪氨酰基自由基，提出了一个模型，其中酪氨酰基自由基的功能是通过从底物水中提取氢原子作为末端配体结合到四个锰离子中的两个。分子氧在最后一步产生，其中氢原子转移和氧-氧键形成在协同反应中一起发生。这一机制建立了光合水氧化和其他酶反应中氨基酸自由基功能之间的清晰类比。
In plants and algae, photosystem II uses light energy to oxidize water to oxygen at a metalloradical site that comprises a tetranuclear manganese cluster and a tyrosyl radical, A model is proposed whereby the tyrosyl radical functions by abstracting hydrogen atoms from substrate water bound as terminal ligands to two of the four manganese ions. Molecular oxygen is produced in the final step in which hydrogen atom transfer and oxygen-oxygen bond formation occur together in a concerted reaction. This mechanism establishes clear analogies between photosynthetic water oxidation and amino acid radical function in other enzymatic reactions.