Solar Energy Research Group, The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama 351, Japan.
Plant Physiol. 1982 Jun;69(6):1418-22. doi: 10.1104/pp.69.6.1418.
Photoactivation of the latent oxygen-evolving system in intact chloroplasts isolated from wheat (Triticum aestivum L.) leaves grown under intermittent flash illumination was investigated, and the following results were obtained: (a) The water-oxidation activity generated on illuminating the isolated intact chloroplasts was as high as that generated in intact leaves, indicating that all the machinery necessary for the activity generation is assembled within intact chloroplasts. (b) The generation of water-oxidation activity was accompanied by enhancement of the activity of diphenylcarbazide-oxidation, and both processes share the same photochemical reaction but with respective rate-limiting dark reactions of different efficiencies. (c) A23187, an ionophore for divalent cations, strongly inhibited the generation of water-oxidation activity but did not affect the activity once generated, which suggested that Mn atoms in the chloroplasts are susceptible to the ionophore before photoactivation but turn immune after photoactivation. (d) The generation of water-oxidation activity was not affected by the inhibitors of ATP formation and CO(2) fixation, but was inhibited by nitrite, methylviologen and phenylmercuric acetate which suppress or inhibit the reduction of ferredoxin in intact chloroplasts. It was inferred that some factor(s) probably present in stroma to be reduced by PSI photoreaction is involved in the process of photoactivation.
研究了在间歇闪光照射下从生长在间歇闪光照射下的小麦（Triticum aestivum L.）叶片中分离的完整叶绿体中潜伏的氧释放系统的光激活，得到以下结果：（a） 当照射分离的完整叶绿体时，产生的水氧化活性与在完整叶片中产生的水氧化活性一样高，这表明生成该活性所需的所有机制都在完整叶绿体中组装。（b） 水氧化活性的产生伴随着二苯卡巴肼氧化活性的增强，这两个过程共享相同的光化学反应，但具有不同效率的各自限速暗反应。（c） A23187，一种二价阳离子载体，强烈抑制水氧化活性的产生，但不影响一旦产生的活性，这表明叶绿体中的 Mn 原子在光激活前对载体敏感，但在光激活后变得免疫。（d） 水氧化活性的产生不受 ATP 形成和 CO2 固定抑制剂的影响，但受亚硝酸盐、甲紫精和苯汞乙酸盐的抑制，这些抑制剂抑制或抑制完整叶绿体中铁氧还蛋白的还原。推断出在PSI 光反应中可能存在于基质中并被还原的某种因子（s）参与了光激活过程。
