NANOSECOND REDUCTION KINETICS OF PHOTOOXIDIZED CHLOROPHYLL-ALPHA-II (P-680) IN SINGLE FLASHES AS A PROBE FOR THE ELECTRON PATHWAY, H+-RELEASE AND CHARGE ACCUMULATION IN THE O-2-EVOLVING COMPLEX
NANOSECOND REDUCTION KINETICS OF PHOTOOXIDIZED CHLOROPHYLL-ALPHA-II (P-680) IN SINGLE FLASHES AS A PROBE FOR THE ELECTRON PATHWAY, H+-RELEASE AND CHARGE ACCUMULATION IN THE O-2-EVOLVING COMPLEX
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DOI：
10.1016/0005-2728(84)90256-1
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发表时间：
1984-01-01
期刊：
影响因子：
--
通讯作者：
WITT, HT
中科院分区：
文献类型：
--
作者：
BRETTEL, K;SCHLODDER, E;WITT, HT
叶绿素的再还原动力学。**图形 **。（P-680+）在第1、第2、第3等之后，给予暗适应的亚叶绿体[菠菜]的闪光已经在纳秒范围内的824 nm处被监测。在第一次闪光之后，以及在第五次闪光之后，叶绿素再次减少。**图形 **。(Chl .**图形 **。在纳秒范围内，几乎是双相的，具有t1/2 = 0。23 ns。在第2次和第3次闪光之后，再还原明显更慢并且是双相的;它可以很好地适应t1/2 50 ns和260 ns。第4次闪蒸后，Chl .** 的再还原动力学图形 **。介于第一次/第五次和第二次/第三次闪光之间。从聚球藻的放氧光系统II粒子样品中获得了类似的对闪光次数的依赖性。考虑到每次闪光前放氧复合物的S态的种群，以下S态与叶绿素的相关性。图形 **。还原动力学和电子转移时间，分别获得：在阶段S 0以及在状态S1 Chl。**图形 **。随着t1/2. apprxeq而减少。23 ns，而在状态S2以及状态S3中，具有t1/2 apeq. 50 ns和260 ns（振幅apeq. 1：1）发生。观察到的多相叶绿素 **图形 **。通过各个电子转移时间的叠加定量地解释了在重复激发下的还原。电子转移到叶绿素的延迟。图形 **。与S 0和S1相比，S2和S3状态可能是由位于O2释放复合物中的1个正电荷的库仑吸引引起的。如果电子释放模式（1，1，1，1）伴随着用于跃迁（S 0 → S2）的质子释放模式（1，0，1，2），则可以解释处于状态S2和S3的带正电荷的释放O2的复合物。S1，S1 →S2，S2 →S3，S3 →S0）。基于线性电子转移的动力学模型从O2释放复合物（S）到Chl .**图形 **。通过2个载体D1和D2，使得实验结果的定量描述成为可能。根据动力学模型，电子转移到叶绿素的延迟。图形 **。在状态S2和S3中的变化通过反应Chl ** 的标准自由能变化Δ G 0的增加来反映。图形 **。D1D2S .**图形 **。Chl α IID 1 + D2 S来自Δ G 0在状态S 0和S1至Δ G 0 apeq中为-90 meV在S2和S3状态下为-20 meV。这一增长约为70毫电子伏可以定量解释的库仑电位的正电荷在O2的演变复杂，估计通过使用点电荷近似。
The re-reduction kinetics of chlorophyll .**GRAPHIC**. (P-680+) after the 1st, 2nd, 3rd, etc., flash given to dark-adapted subchloroplasts [spinach] have been monitored at 824 nm in the nanosecond range. After the 1st flash and, again, after the 5th flash, the re-reduction of chlorophyll .**GRAPHIC**. (Chl .**GRAPHIC**. in the nanosecond range is nearly monophasic with t1/2 .apprxeq. 23 ns. After the 2nd and 3rd flash, the re-reduction is significantly slower and biphasic; it can be well-adapted with t1/2 .apprxeq. 50 ns and .apprxeq. 260 ns. After the 4th flash, the re-reduction kinetics of Chl .**GRAPHIC**. are intermediate between the 1st/5th and 2nd/3rd flash. A similar dependence on flash number was obtained with a sample of oxygen-evolving Photosystem II particles from Synechococcus sp. Considering the populations of the S-states of the O2-evolving complex before each flash, the following correlation of S-states to Chl .**GRAPHIC**. reduction kinetics and electron transfer times, respectively, is obtained: in stage S0 as well as in state S1 Chl .**GRAPHIC**. is reduced with t1/2 .apprxeq. 23 ns, whereas in state S2 as well as state S3 a biphasic reduction with t1/2 .apprxeq. 50 ns and .apprxeq. 260 ns (ratio of the amplitudes .apprxeq. 1:1) occurs. The observed multiphasic Chl .**GRAPHIC**. reduction under repetitive excitation is quantitatively explained by a superposition of the individual electron transfer times. The retardation of electron transfer to Chl .**GRAPHIC**. in states S2 and S3 as compared to S0 and S1 is probably caused by Coulomb attraction by 1 positive charge located in the O2-evolving complex. A positively charged O2-evolving complex in states S2 and S3 can be explained if the electron release pattern (1,1,1,1) is accompanied by a proton release pattern (1,0,1,2) for the transitions (S0 .fwdarw. S1, S1 .fwdarw. S2, S2 .fwdarw. S3, S3 .fwdarw. S0). A kinetic model based on linear electron transfer from the O2-evolving complex (S) to Chl .**GRAPHIC**. via 2 carriers, D1 and D2, makes a quantitative description of the experimental results possible. According to the kinetic model, the retardation of electron transfer to Chl .**GRAPHIC**. in states S2 and S3 is reflected by an increase in the change of standard free energy, .DELTA.G0, of the reaction Chl .**GRAPHIC**. D1D2S .**GRAPHIC**. Chl .alpha.IID1+D2S from .DELTA.G0 .apprxeq. -90 meV in states S0 and S1 to .DELTA.G0 .apprxeq. -20 meV in states S2 and S3. This increase by .apprxeq. 70 meV can be quantitatively explained by the Coulomb potential of the positive charge in the O2-evolving complex, estimated by using the point charge approximation.