Primary radical pair in the Photosystem II reaction centre
Primary radical pair in the Photosystem II reaction centre
复制标题
光系统 II 反应中心的初级自由基对
DOI：
10.1016/0005-2728(87)90147-2
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
K. Satoh
中科院分区：
文献类型：
--
作者：
Yuichiro Takahashi;Ö. Hansson;P. Mathis;K. Satoh
摘要 初级光系统 II (PS II) 反应已通过纳秒分辨率的闪光吸收光谱进行了研究。在缺乏 47-kDa 和 43-kDa 叶绿素结合多肽的分离反应中心中，通过闪光立即诱导吸收变化 (ΔA)。差异光谱 (450–560 nm, 820 nm) 表明自由基对 (P-680+, Pheo−) 的形成，在 120 K 下以 t 1 2= 40 ns 衰减。在闪光后 140 ns，ΔA 可归因于 P-680 (3 P-680) 和类胡萝卜素 (3 Car, λ max= 545) 的三重态纳米）。 3 Car 形成的产率约为 3%，并且随 t 1 2 ≈ 12 ns 上升。在 276 K 时，自由基对衰变，t 1 2≈ 32 ns。每 20 个叶绿素形成 1 个自由基对。如果 3 P-680 形成为自由基对重组产物，276 K 时产率为 23%（10 K 时产率为 80%），并且 3 Car 仅在少数颜料复合物中形成，则可以最好地解释数据。在旨在减少脱镁叶绿素的条件下（添加连二亚硫酸盐和甲基紫精，加上连续照明），820 nm 处的 ΔA 消失。关闭常亮灯后，信号重新出现。还研究了更完整的 PS II 颗粒（核心复合物）。在820 nm处，数据显示P-680+在氧化条件下形成，并在微秒时间范围内重新还原。在还原条件下，初级双自由基衰变时间为 t 1 2= 25 ns。形成 3 P-680，其性质类似于孤立反应中心的性质。还形成了 3 Car (λ max= 535 nm)。结果表明，PS II反应中心与紫色细菌的反应中心具有很强的功能相似性。类胡萝卜素的行为是一个显着的例外。根据荧光测量，初级双自由基的衰减比预期的要慢得多。
Abstract Primary Photosystem II (PS II) reactions have been studied by flash absorption spectroscopy with nanosecond resolution. In isolated reaction centers which are devoid of the 47-and 43-kDa chlorophyll-binding polypeptides, an absorption change (ΔA) is induced immediately by a flash. The difference spectrum (450–560 nm, 820 nm) indicates the formation of a radical pair (P-680+, Pheo−) decaying with t 1 2= 40 ns at 120 K. At 140 ns after the flash the ΔA can be attributed to the triplet state of P-680 (3 P-680) and of a carotenoid (3 Car, λ max= 545 nm). 3 Car is formed with a yield of≈ 3% and it rises with t 1 2≈ 12 ns. At 276 K, the radical pair decays, with t 1 2≈ 32 ns. One radical pair is formed per 20 chlorophylls. The data are best interpreted if 3 P-680 is formed as a product of radical pair recombination with a yield of 23% at 276 K (80% at 10 K) and if 3 Car is formed only in a minority of pigment complexes. The ΔA at 820 nm disappear under conditions (addition of dithionite and methyl viologen, plus continuous illumination) designed to reduce pheophytin. The signals reappear after turning off the continuous light. More intact PS II particles (core complex) were also studied. At 820 nm, the data show that P-680+ is formed under oxidizing conditions and is re-reduced in the microsecond time range. Under reducing conditions the primary biradical decays with t 1 2= 25 ns. 3 P-680 is formed, with properties analogous to those in isolated reaction centers. 3 Car is also formed (λ max= 535 nm). The results show that the PS II reaction center has strong functional analogies with the reaction center of purple bacteria. The behavior of the carotenoid is a remarkable exception. The primary biradical decays much more slowly than expected on the basis of fluorescence measurements.
来自球形红假单胞菌的分离光合反应中心的纳秒荧光。
DOI：
10.1016/0005-2728(84)90205-6
发表时间：
1984
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Woodbury,NW;Parson,WW
通讯作者：
Parson,WW