Active and resting states of the O2-evolving complex of photosystem II.
Active and resting states of the O2-evolving complex of photosystem II.
复制标题
光系统 II 的 O2 演化复合体的活性和静止状态。
DOI：
10.1021/bi00333a035
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发表时间：
1985
期刊：
影响因子：
2.9
通讯作者：
Brudvig,GW
中科院分区：
文献类型：
--
作者：
Beck,WF;dePaula,JC;Brudvig,GW
耶鲁大学化学系，纽黑文，康涅狄格州 06511 收稿日期：1984 年 5 月 11 日；修订稿于 1984 年 12 月 28 日收到摘要：在暗适应过程中，菠菜光系统 II (PSII) 的 02 演化复合体 (OEC) 发生变化，影响了 Mn 位点的结构和 OEC 的化学性质，这一点通过低温电子顺磁共振 (EPR) 光谱和 02 测量确定。 S2 态多线 EPR 信号由 OEC 中的含锰物质产生，在暗适应 PSII 膜或类囊体的长期（0℃ 4 小时）和短期（0℃ 6 分钟）中表现出不同的特性。在长期暗适应样品中产生此 EPR 信号的最佳温度为 200 K，而短期暗适应样品则为 170 K。然而，在短期暗适应样本中，170 K 的照明产生的 EPR 信号与 160 K 或更低的照明相比具有不同的超精细结构和更宽的视场范围。相比之下，长期暗适应样本中产生的 S2 态 EPR 信号的线形与照明温度无关。 EPR检测到的OEC Mn位点在暗适应过程中发生的变化与PSII或类囊体膜的O 2 消耗活性的变化相关。 PSII膜和类囊体膜在光照后缓慢消耗O 2 ，但仅当存在功能性OEC和过量还原剂时。我们将这种O 2 缓慢消耗归因于OEC在黑暗中催化还原O 2 。暗适应过程中02消耗率下降；尽管存在过量的还原剂，但长期暗适应的 PSII 或类囊体膜不会消耗 02。 EPR检测到的OEC的Mn位点的变化和PSII或类囊体膜中观察到的O 2 消耗活性的下降以相同的时间常数发生。提出在暗适应期间OEC的Mn位点发生结构变化，改变PSII供体侧的电子传输性质并导致从活跃的、消耗O 2 的状态转变为不能消耗O 2 的静止状态。
Department of Chemistry, Yale University, New Haven, Connecticut 06511 Received May 11, 1984; Revised Manuscript Received December 28, 1984 abstract: During dark adaptation, a change in the 02-evolving complex (OEC) of spinach photosystem II (PSII) occurs that affects both the structure of the Mn site and the chemical properties of the OEC, as determined from low-temperature electron paramagnetic resonance(EPR) spectroscopy and 02 mea-surements. The S2-state multiline EPR signal, arisingfrom a Mn-containing species in the OEC, exhibits different properties in long-term (4 h at 0 C) and short-term (6 min at 0 C) dark-adapted PSII membranes or thylakoids. The optimal temperature for producing this EPR signal in long-term dark-adapted samples is 200 K compared to 170 K for short-term dark-adapted samples. However, in short-term dark-adapted samples, illumination at 170 K produces an EPR signal with a different hyperfine structure and a wider field range than does illumination at 160 K or below. In contrast, the line shape of the S2-state EPR signal produced in long-term dark-adapted samples is independent of the illumination temperature. The EPR-detected change in the Mn site of the OECthat occurs during dark adaptation is correlated with a change in 02 consumptionactivity of PSII or thylakoid membranes. PSII membranes and thylakoid membranes slowly consume 02 following illumination, but onlywhen a functional OEC and excess reductant are present.We assign this slow consumption of 02 to a catalytic reduction of 02 by the OEC in the dark. Therate of 02 consumption decreases during dark adaptation; long-term dark-adapted PSII or thylakoid membranes do not consume 02 despite the presence of excess reductant. The EPR-detected change in the Mn site of the OEC and the decline of the 02 consumption activity observed in PSII or thylakoid membranes occur with the same time constant. It is proposed that a structural change in the Mn site of the OEC occurs during dark adaptation, changing the electron-transport properties of the donor side of PSII and causing a conversion from an active, 02-consuming state to a resting state incapable of 02 consumption.