Max-Volmer-Institut für Biophysikalische und Physikalische Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, 1000, Berlin 12, BRD.
Photosynth Res. 1986 Jan;9(1-2):71-8. doi: 10.1007/BF00029733.
Oxygen evolution and reduction kinetics of the photooxidized Chl-aII (+) have been measured in oxygen-evolving complexes from the thermophilic cyanobacterium Synechococcus sp. 1. Incubation of PS II particles with acetate resulted in an inhibition of oxygen evolution and a retardation of the Chl-aII (+)=reduction kinetics from the nanosecond range to the microsecond range, indicating a modification of the donor side of photosystem II (PS II). 2. After the first two flashes given to a dark-adapted, acetate treated sample, Chl-aII (+) was re-reduced with a half-life time of 160 μs by a component of the donor side of PS II. Under repetitive excitation Chl-aII (+) was re-reduced in 500 μs by electron back reaction from the primary acceptor QA (-) (X-320(-)). Obviously, in the presence of acetate only two electrons are available from the donor side. 3. Both oxygen evolution and nanosecond reduction kinetics of Chl-aII (+) were restored to the control level when acetate was removed. 4. The results indicate a tight coupling between O2 evolution and nanosecond reduction kinetics of Chl-aII (+). 5. The reversible inhibition is probably due to a replacement of Cl(-) by acetate within the water splitting enzyme. 6. Due to its strongly retarded kinetics, the reversibly modified system may facilitate investigations of the mechanism of the donor side.
已在嗜热蓝藻 Synechococcus sp. 1 的放氧复合体内测量了光氧化 Chl-aII(+)的氧释放和还原动力学。用乙酸盐孵育 PS II 颗粒导致氧释放抑制和 Chl-aII(+)还原动力学从纳秒范围延迟到微秒范围，表明光合作用系统 II (PS II) 的供体侧发生了修饰。2. 在给暗适应的、用乙酸盐处理的样品进行前两个闪光后，Chl-aII(+)通过 PS II 供体侧的一个组件以 160 μs 的半衰期被重新还原。在重复激发下，Chl-aII(+)通过来自原受体 QA(-) (X-320(-))的电子反向反应在 500 μs 内被还原。显然，在存在乙酸盐的情况下，只有两个电子从供体侧获得。3. 当去除乙酸盐时，氧释放和 Chl-aII(+)的纳秒还原动力学都恢复到对照水平。4. 结果表明 O2 释放和 Chl-aII(+)的纳秒还原动力学之间存在紧密偶联。5. 可逆抑制可能是由于水分解酶内 Cl(-)被乙酸盐取代。6. 由于其动力学明显延迟，可还原的修饰系统可能有助于供体侧机制的研究。
