在光系统II氧气演化复合体的乙酸结合:一个S(2) 状态的多线信号ESEEM研究ESEEM研究
Keri L Clemens1, Dee Ann Force, R David Britt
1Department of Chemistry, University of California, Davis, CA 95616-0935, USA.
Journal of the American Chemical Society
|September 5, 2002
概括
乙酸直接与光系II (PSII) 中的 (Mn) 集群结合,这表明化物离子也结合了Mn集群. 乙酸结合会取代水分子,但不会影响丁结合或甲醇结合.
科学领域:
- 生物化学 生物化学
- 光合作用研究研究光合作用.
- 生物有机化学 生物有机化学
背景情况:
- 光系统II (PSII) 对于氧光合作用至关重要.
- 在PSII内部的 (Mn) 集群是水氧化的核心.
- 已知PSII的乙酸抑制与化物 (Cl ((-)) 离子具有竞争力.
研究的目的:
- 为了确定乙在PSII中的结合部位和相互作用.
- 为了研究酸盐结合对Mn集群的结构影响.
- 为了阐明酸盐,化物和水结合点之间的关系.
主要方法:
- 电子旋转回声封膜调制 (ESEEM) 光谱法被用来探测Mn集群相互作用.
- 用了对磁性NO来选择性地灭Y. ) (z) 氨酸信号. 氨酸信号. 氨酸信号.
- 用酸和各种溶剂 (D(2) O,甲醇,DMSO) 来研究结合动力学.
主要成果:
- 乙酸直接与Mn集群结合,由特定的 (2) H 超精密合物证明.
- 离子可能也将团结起来,因为酸盐结合是竞争性的.
- 乙酸结合将密切相关的子 (水) 从Mn集群中取代,但不会改变Mn-histidine结合.
- 在乙酸盐的存在下,甲醇仍然可以与Mn集群结合,而DMSO结合则受到阻碍.
结论:
- 乙酸直接与PSII中的Mn集群结合,提供了对像Cl这样的必需辅助因子的结合部位的洞察力.
- 乙酸结合影响了Mn团中的水分子的可访问性,但保持了Mn-histidine协调的完整性.
- 该研究澄清了Mn团中的竞争性结合动态,区分了小分子和大分子相互作用.
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