Institute of Soil Science and Photosynthesis, Russian Academy of Science, 142292, Pushchino, Moscow Region, Russia.
Photosynth Res. 1993 Jan;38(3):409-16. doi: 10.1007/BF00046768.
The present study describes the formation of different forms of peroxide in Photosystem II (PS II) by using a chemiluminescence detection technique. Four chemiluminescence signals (A, B, C and D) of the luminolperoxidase (Lu-Per) system, which detects peroxide, are found in illuminated O2-evolving Photosystem II (PS II) membrane fragments isolated from spinach. Signal A ('free peroxide') peaking around 0.2-0.3 s after mixing PS II membrane fragments with Lu-Per is eliminated by catalase or removal of oxygen from the suspension and ascribed to O2 interaction with reduced PS II electron acceptors. In contrast, signal B peaking around 1.5 min remains largely unaffected under anaerobic conditions, as well as in the presence of catalase (20 μg/ml). Under flash illumination the extent of this signal exhibits a weak period four oscillation (maximum at third and 7th flash). Its yield increases up to the third flash, but is close to zero in the fourth flash. An analogous behaviour is observed in flashes 5 to 8. Signal B is ascribed to Lu-Per interaction with the water-oxidizing system being in S2 and/or S3-state. Signal C ('bound peroxide') detected as free peroxide after acid decomposition of illuminated PS II particles is observed on the 1 st flash and oscillates with period 2 with superposition of period 4. It is evidently related to peroxide either released from S2 or formed at S2 upon acid shock treatment. Signal D ('slowly released peroxide') peaking around 2-3 s after mixing is observed in samples after various treatments (LCC-incubation, washing with 1 M NaCl at pH 8 or with 1 M CaCl2, Cl(-)-depletion) that lead to at least partial removal of the extrinsic proteins of 18, 24 and 33 kDa without Mn extraction. The average amplitude of this signal corresponds with a yield of about 0.2 H2O2 molecules per RC and flash. In a flash train, the extent of signal D exhibits an oscillation pattern with a minimum at the 3rd flash. We assume that these treatments increase the release of 'bound' peroxide (upon injection into the Lu-Per assay) either formed in the normal oxidative pathway of the water oxidase in the S2 or the S3-state or give rise to peroxide formation due to higher accessibility of the Mn-cluster to water molecules.
本研究采用化学发光检测技术描述了光合作用系统 II（PS II）中不同形式过氧化物的形成。在从菠菜中分离出的受光激发的产氧 PS II 膜片段中，发现了发光物过氧化物酶（Lu-Per）系统的四种化学发光信号（A、B、C 和 D），该系统检测过氧化物。信号 A（“游离过氧化物”）在与 Lu-Per 混合后约 0.2-0.3 秒达到峰值，在悬浮液中去除氧气或添加过氧化氢酶后会被消除，并归因于 O2 与还原 PS II 电子受体的相互作用。相比之下，在无氧条件下以及存在过氧化氢酶（20 μg/ml）时，信号 B 约 1.5 分钟达到峰值，基本不受影响。在闪光照射下，该信号的程度表现出微弱的四周期振荡（第三和第七闪光时达到最大值）。在第三闪光时，其产量增加，但在第四闪光时接近零。在第五到第八闪光时观察到类似的行为。信号 B 归因于 Lu-Per 与处于 S2 和/或 S3 状态的水氧化系统相互作用。在受光 PS II 颗粒的酸分解后作为游离过氧化物检测到的信号 C（“结合过氧化物”）在第一闪光时被检测到，并以 2 的周期振荡，叠加 4 的周期。它显然与 S2 释放的过氧化物或酸冲击处理时在 S2 形成的过氧化物有关。在混合后约 2-3 秒达到峰值的信号 D（“缓慢释放的过氧化物”）在经过各种处理（LCC 孵育、在 pH 8 用 1 M NaCl 或 1 M CaCl2 洗涤、Cl(-)耗尽）的样品中被观察到，这些处理至少会导致至少部分去除 18、24 和 33 kDa 的外在蛋白，而锰并未被提取。该信号的平均幅度与每个 RC 和闪光约 0.2 H2O2 分子的产率相对应。在闪光序列中，信号 D 的程度表现出一种振荡模式，在第三闪光时达到最小值。我们假设这些处理会增加“结合”过氧化物的释放（在注入 Lu-Per 测定中），要么是在水氧化酶的正常氧化途径中在 S2 或 S3 状态下形成的，要么是由于 Mn 簇对水分子的更高可及性导致过氧化物形成。
