氨结合到光系统 II 放氧复合物的 dangler 锰上。
Ammonia Binds to the Dangler Manganese of the Photosystem II Oxygen-Evolving Complex.
机构信息
†Department of Chemistry, University of California, Davis, Davis, California 95616, United States.
‡Department of Biochemistry, University of California, Riverside, Riverside, California 92521, United States.
出版信息
J Am Chem Soc. 2015 Jul 15;137(27):8829-37. doi: 10.1021/jacs.5b04768. Epub 2015 Jul 2.
High-resolution X-ray structures of photosystem II reveal several potential substrate binding sites at the water-oxidizing/oxygen-evolving 4MnCa cluster. Aspartate-61 of the D1 protein hydrogen bonds with one such water (W1), which is bound to the dangler Mn4A of the oxygen-evolving complex. Comparison of pulse EPR spectra of (14)NH3 and (15)NH3 bound to wild-type Synechocystis PSII and a D1-D61A mutant lacking this hydrogen-bonding interaction demonstrates that ammonia binds as a terminal NH3 at this dangler Mn4A site and not as a partially deprotonated bridge between two metal centers. The implications of this finding on identifying the binding sites of the substrate and the subsequent mechanism of dioxygen formation are discussed.
高分辨率的光合作用 II 光系统 X 射线结构揭示了在水氧化/氧气释放 4MnCa 簇中有几个潜在的底物结合位点。D1 蛋白中的天冬氨酸-61 与一个这样的水分子（W1）形成氢键，该水分子与氧气释放复合物的摆动 Mn4A 结合。对野生型集胞藻 PSII 和缺乏这种氢键相互作用的 D1-D61A 突变体结合的 (14)NH3 和 (15)NH3 的脉冲 EPR 光谱的比较表明，氨作为末端 NH3 结合在这个摆动 Mn4A 位点上，而不是作为两个金属中心之间部分去质子化的桥。这一发现对确定底物的结合位点以及随后的双氧形成机制的意义进行了讨论。
Zotero 插件