COOPERATION OF CHARGES IN PHOTOSYNTHETIC O2 EVOLUTION .1. A LINEAR 4STEP MECHANISM
COOPERATION OF CHARGES IN PHOTOSYNTHETIC O2 EVOLUTION .1. A LINEAR 4STEP MECHANISM
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DOI：
10.1111/j.1751-1097.1970.tb06017.x
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发表时间：
1970-01-01
影响因子：
3.3
通讯作者：
MCGLOIN, M
中科院分区：
文献类型：
--
作者：
KOK, B;FORBUSH, B;MCGLOIN, M
利用离体叶绿体和Joliot和Joliot[6]描述的技术，我们研究了弱光和闪光中O2的演变，以分析光诱导的O2前体和它们在黑暗中的衰变之间的相互作用。本研究的主要观察结果和结论如下：1.闪光总是产生相同数量的氧化当量，无论是作为前体还是作为O2。2.在稳态光合作用过程中存在的不稳定前体当量的数量是每个光化学捕获中心1.2。3.四个光化学形成的氧化等价物的合作基本上发生在各个反应中心和最后的O2演变步骤是一个量子过程。4.数据与线性四步机制相容，其中捕获中心或相关催化剂（S）连续积累四个+电荷。S4+状态产生O2并返回到基态S 0。5.除了S 0外，第一氧化态S+在黑暗中也是稳定的，两个更高的态S2+和S3+在黑暗中不稳定。6.一些光氧化步骤的弛豫时间进行了估计。最快的反应，可能是S *1←S2，其（前）半衰期≤ 200 μsec。S * 2状态和可能还有S * 0状态的处理稍微慢一些（大约300-400 μsec）。
Using isolated chloroplasts and techniques as described by Joliot and Joliot[6] we studied the evolution of O2in weak light and light flashes to analyze the interactions between light induced O2precursors and their decay in darkness. The following observations and conclusions are reported: 1. Light flashes always produce the same number of oxidizing equivalents either as precursor or as O2. 2. The number of unstable precursor equivalents present during steady state photosynthesis is ∼ 1.2 per photochemical trapping center. 3. The cooperation of the four photochemically formed oxidizing equivalents occurs essentially in the individual reaction centers and the final O2evolution step is a one quantum process. 4. The data are compatible with a linear four step mechanism in which a trapping center, or an associated catalyst, (S) successively accumulates four + charges. TheS4+state produces O2and returns to the ground stateS0. 5. BesidesS0also the first oxidized stateS+is stable in the dark, the two higher states, S2+and S3+are not. 6. The relaxation times of some of the photooxidation steps were estimated. The fastest reaction, presumablyS*1←S2, has a (first) half time ≤ 200 μsec. TheS*2state and probably also theS*0state are processed somewhat more slowly (˜ 300–400 μsec).