Department of Plant Physiology, Agricultural University, Arboretumlaan 4, 6703 BD, Wageningen, The Netherlands.
Photosynth Res. 1993 Jan;38(3):309-14. doi: 10.1007/BF00046755.
In Photosystem II (PS II), water is oxidized to molecular oxygen and plastoquinone is reduced to plastoquinol. The oxidation of water requires the accumulation of four oxidizing equivalents, through the so-called S-states of the oxygen evolving complex; the production of plastoquinol requires the accumulation of two reducing equivalents on a bound plastoquinone, QB. It has been generally believed that during the flash-induced transition of each of the S-states (Sn → Sn+1, where n=0, 1, 2 and 3), a certain small but equal fraction of the PS II reaction centers are unable to function and, thus, 'miss' being turned over. We used thoroughly dark-adapted thylakoids from peas (Pisum sativum) and Chenopodium album (susceptible and resistant to atrazine) starting with 100% of the oxygen evolving complex in the S1 state. Thylakoids were illuminated with saturating flashes, providing a double hit parameter of about 0.07. Our experimental data on flashnumber dependent oscillations in the amount of oxygen per flash fit very well with a binary pattern of misses: 0, 0.2, 0, 0.4 during S0 → S1, S1 → S2, S2 → S3 and S3 → S0 transitions. Addition of 2 mM ferricyanide appears to shift this pattern by one flash. These results are consistent with the 'bicycle' model recently proposed by V. P. Shinkarev and C. A. Wraight (Oxygen evolution in photosynthesis: From unicycle to bicycle, 1993, Proc Natl Acad Sci USA 90: 1834-1838), where misses are due to the presence of P(+) or QA (-) among the various equilibrium states of PS II centers.
在光系统 II（PS II）中，水被氧化为分子氧，质体醌被还原为质体醇。水的氧化需要通过所谓的氧释放复合物的 S 态积累四个氧化当量；质体醇的产生需要在结合的质体醌 QB 上积累两个还原当量。人们普遍认为，在每个 S 态（Sn → Sn+1，其中 n=0、1、2 和 3）的闪光诱导跃迁期间，一定比例的 PS II 反应中心无法正常工作，因此“错过”被翻转。我们使用完全黑暗适应的豌豆（Pisum sativum）和藜（对莠去津敏感和耐受）类囊体，起始时氧释放复合物全部处于 S1 态。类囊体用饱和闪光照射，提供大约 0.07 的双击中参数。我们关于每个闪光的氧产量的闪光数依赖性振荡的实验数据非常符合错过的二进制模式：在 S0 → S1、S1 → S2、S2 → S3 和 S3 → S0 跃迁期间，分别为 0、0.2、0、0.4。添加 2 mM 铁氰化物似乎会使这种模式移动一个闪光。这些结果与 V. P. Shinkarev 和 C. A. Wraight 最近提出的“自行车”模型一致（光合作用中的氧气进化：从单轮到自行车，1993 年，美国国家科学院院刊 90: 1834-1838），其中错过是由于 PS II 中心的各种平衡态中存在 P(+)或 QA (-)。
