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タイトル: | Mechanism of tyrosine D oxidation in Photosystem II |
著者: | Saito, Keisuke Rutherford, A William Ishikita, Hiroshi |
著者名の別形: | 石北, 央 |
キーワード: | oxygen-evolving complex proton-coupled electron transfer reaction center evolution controlling electron transfer rate hydrogen bond direction switching |
発行日: | 18-Apr-2013 |
出版者: | National Academy of Sciences |
誌名: | Proceedings of the National Academy of Sciences of the United States of America |
抄録: | Using quantum mechanics/molecular mechanics calculations and the 1.9-Å crystal structure of Photosystem II [Umena Y, Kawakami K, Shen J-R, Kamiya N (2011) Nature 473(7345):55–60], we investigated the H-bonding environment of the redox-active tyrosine D (TyrD) and obtained insights that help explain its slow redox kinetics and the stability of TyrD•. The water molecule distal to TyrD, located ∼4 Å away from the phenolic O of TyrD, corresponds to the presence of the tyrosyl radical state. The water molecule proximal to TyrD, in H-bonding distance to the phenolic O of TyrD, corresponds to the presence of the unoxidized tyrosine. The H+ released on oxidation of TyrD is transferred to the proximal water, which shifts to the distal position, triggering a concerted proton transfer pathway involving D2-Arg180 and a series of waters, through which the proton reaches the aqueous phase at D2-His61. The water movement linked to the ejection of the proton from the hydrophobic environment near TyrD makes oxidation slow and quasiirreversible, explaining the great stability of the TyrD•. A symmetry-related proton pathway associated with tyrosine Z is pointed out, and this is associated with one of the Cl− sites. This may represent a proton pathway functional in the water oxidation cycle. |
記述: | 光合成酸素発生反応で利用される蛋白質内のプロトン移動経路を発見 : 人工光合成系の設計やバイオエネルギーの生産性向上に指針. 京都大学プレスリリース. 2013-04-16. |
著作権等: | ©2013 by the National Academy of Sciences |
URI: | http://hdl.handle.net/2433/173375 |
DOI(出版社版): | 10.1073/pnas.1300817110 |
PubMed ID: | 23599284 |
関連リンク: | http://www.kyoto-u.ac.jp/ja/news_data/h/h1/news6/2013/130416_1.htm |
出現コレクション: | 学術雑誌掲載論文等 |
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