On the structure of the manganese complex of photosystem II: extended-range EXAFS data and specific atomic-resolution models for four S-states
On the structure of the manganese complex of photosystem II: extended-range EXAFS data and specific atomic-resolution models for four S-states
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DOI：
10.1098/rstb.2007.2220
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发表时间：
2008-03-27
影响因子：
6.3
通讯作者：
Haumann, Michael
中科院分区：
文献类型：
--
作者：
Dau, Holger;Grundmeier, Alexander;Haumann, Michael
通过 PSII 膜颗粒上的 X 射线吸收光谱研究了与光系统 II (PSII) 蛋白质结合的水氧化锰络合物。使用扩展范围来收集扩展 X 射线吸收精细结构 (EXAFS) 数据（高达 16.6 埃(-1)）。 EXAFS 表明存在两个接近 2.7 埃的 Mn-Mn 距离（每个 Mn4Ca 复合物）；低于 2.9 埃的第三个 Mn-Mn 距离的存在至少是不确定的。有趣的是，在扩展范围数据中清楚地解析了 3.7 埃的距离，并暂时将其分配给 Mn-Mn 距离。考虑到上述 EXAFS 结果（除其他外），我们提出了 PSII 锰配合物结构的模型，该模型不同于以前的原子分辨率模型。强调假设特征，我们对所有半稳定 S 态提出：(i) Mn4Ca(mu-O)(n) 核心的结构，(ii) 氨基酸环境模型，以及 (iii) 将不同的 Mn 氧化态分配给所有单独的 Mn 离子。这种特定的工作模型可以允许与实验和理论结果相比对其各种特征进行讨论、验证和无效。
The water-oxidizing manganese complex bound to the proteins of photosystem II (PSII) was studied by X-ray absorption spectroscopy on PSII membrane particles. An extended range for collection of extended X-ray absorption fine-structure (EXAFS) data was used (up to 16.6 angstrom(-1)). The EXAFS suggests the presence of two Mn-Mn distances close to 2.7 angstrom (per Mn4Ca complex); the existence of a third Mn-Mn distance below 2.9 angstrom is at least uncertain. Interestingly, a distance of 3.7 angstrom is clearly resolved in the extended-range data and tentatively assigned to a Mn-Mn distance. Taking into account the above EXAFS results (inter alia), we present a model for the structure of the PSII manganese complex, which differs from previous atomic-resolution models. Emphasizing the hypothetical character, we propose for all semi-stable S-states: (i) a structure of the Mn4Ca(mu-O)(n) core, (ii) a model of the amino acid environment, and (iii) assignments of distinct Mn oxidation states to all the individual Mn ions. This specific working model may permit discussion, verification and invalidation of its various features in comparison with experimental and theoretical findings.