Christen G, Reifarth F, Renger G
Max-Volmer-Institute for Biophysical Chemistry and Biochemistry, Technical University Berlin, Germany.
FEBS Lett. 1998 Jun 5;429(1):49-52. doi: 10.1016/s0014-5793(98)00552-3.
The origin of the '35-micros kinetics' of P680(+.) reduction in photosystem II (PS II) with an intact water oxidising complex has been analysed by comparative measurements of laser flash induced changes of the 830-nm absorption and the relative quantum yield of chlorophyll (Chl) fluorescence. The latter parameter was monitored at a time resolution of 500 ns by using newly developed home built equipment [Reifarth, F., Christen, G. and Renger, G. (1997) Photosynth. Res. 51, 231-2421. It was found that: (i) the amplitudes of the unresolved ns-kinetics of both 830-nm absorption changes and the rise of fluorescence yield exhibit virtually the same period four oscillation pattern when dark adapted samples are excited with a train of saturating laser flashes; (ii) the corresponding oscillation patterns of the normalised extent of the 35-micros kinetics under identical excitation conditions are strikingly different with maxima after the 3rd and 5th flash for the 830-nm absorption changes vs. pronounced maxima after the 4th and 8th flash for the rise of the fluorescence yield. The period four oscillations unambiguously show that the '35-micros kinetics' of P680(+.) reduction are characteristic for reactions in PS II entities with an intact water oxidising complex. However, the disparity of the oscillation patterns of (ii) indicates that in contrast to the ns components of P680(+.) reduction the 35-micros kinetics do not reflect exclusively an electron transfer from Y(Z) to P680(+.). It is inferred that a more complex reaction takes place which comprises at least two processes: (a) P680(+.) reduction by Y(Z) and (b) coupled and/or competing reaction(s) which give rise to additional changes of the chlorophyll fluorescence yield.
通过对激光闪光诱导的830 nm吸收变化和叶绿素（Chl）荧光相对量子产率的比较测量，分析了具有完整水氧化复合物的光系统II（PS II）中P680(+.)还原的“35微秒动力学”的起源。使用新开发的自制设备，以500 ns的时间分辨率监测后一参数[Reifarth, F., Christen, G. 和Renger, G. (1997) Photosynth. Res. 51, 231 - 2421]。结果发现：(i) 当用一系列饱和激光闪光激发暗适应样品时，830 nm吸收变化的未解析纳秒动力学幅度和荧光产率上升呈现出几乎相同的四周期振荡模式；(ii) 在相同激发条件下，35微秒动力学归一化程度的相应振荡模式明显不同，830 nm吸收变化在第3次和第5次闪光后出现最大值，而荧光产率上升在第4次和第8次闪光后出现明显最大值。四周期振荡明确表明，P680(+.)还原的“35微秒动力学”是具有完整水氧化复合物的PS II实体中反应的特征。然而，(ii)中振荡模式的差异表明，与P680(+.)还原的纳秒成分不同，35微秒动力学并不完全反映从Y(Z)到P680(+.)的电子转移。据推断，发生了一个更复杂的反应，该反应至少包括两个过程：(a) Y(Z)对P680(+.)的还原，以及(b) 导致叶绿素荧光产率额外变化的耦合和/或竞争反应。
