Evidence for Spontaneous Structural Changes in a Dark-Adapted State of Photosystem II

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• 作者：Kelly M. Halverson ; Bridgette A. Barry
• 刊名：Biophysical Journal
• 出版年：2003
• 出版时间：October 2003
• 年：2003
• 卷：85
• 期：4
• 页码：2581-2588
• 全文大小：168 K

文摘

Photosystem II catalyzes photosynthetic water oxidation in plants, green algae, and cyanobacteria. The manganese-containing active site cycles through a series of five oxidation states, S_n, where n refers to the number of oxidizing equivalents stored. In this report, reaction-induced Fourier transform infrared and electron paramagnetic resonance spectra of the S₁-to-S₂ transition are presented. These data suggest that changes in carboxylate ligation to manganese, changes in secondary structure, and/or changes in polarity occur during dark adaptation in the S₁ state. These spontaneous structural changes are attributed to a S₁′ intermediate, at the same oxidation level as S₁, in the process of photosynthetic water oxidation.