Allakhverdiev S I, Karacan M S, Somer G, Karacan N, Khan E M, Rane S Y, Padhye S, Klimov V V, Renger G
Institute of Soil Science and Photosynthesis, RAS, Pushchino, Moscow Region, Russia.
Biochemistry. 1994 Oct 11;33(40):12210-4. doi: 10.1021/bi00206a025.
The efficiency of synthetic binuclear manganese complexes in reconstituting PS II electron flow and oxygen-evolution capacity was analyzed in PS II enriched preparations deprived of their manganese and of the extrinsic regulatory subunits. Measurements of the variable fluorescence induced by actinic illumination with continuous light led to the following results: (a) the synthetic binuclear complexes are more efficient than MnCl2 in establishing a PS II electron flow; (b) an almost complete restoration is achieved at concentrations of these complexes that correspond with an overall stoichiometry of two manganese per PS II; and (c) the electron flow restored by the binuclear manganese complexes closely resembles that of normal O2-evolving PS II preparations in its resistance to addition of 50 microM EDTA, while that supported by MnCl2 is practically completely suppressed at the same chelator concentration. The rate of O2 evolution was used as a measure of the capability to function as manganese source in reconstitution of the oxygen evolution capacity. It was found that (i) as in the case of PS II electron transport, the synthetic binuclear manganese complexes are significantly more efficient than MnCl2; (ii) with respect to the manganese concentration, the maximum effect is achieved with a mu-oxo bridged binuclear Mn(III) complex (symbolized by M-3) at concentrations corresponding to four manganese per PS II; and (iii) at all concentrations of binuclear manganese complex M-3 a significantly higher restoration of the O2 evolution rate is achieved if the reconstitution assay contains in addition the extrinsic regulatory 33 kDa protein (PS II-O protein).(ABSTRACT TRUNCATED AT 250 WORDS)
在去除了锰和外在调节亚基的富含光系统II（PS II）的制剂中，分析了合成双核锰配合物在重建PS II电子流和放氧能力方面的效率。用连续光进行光化照射诱导的可变荧光测量得出以下结果：（a）在建立PS II电子流方面，合成双核配合物比氯化锰更有效；（b）在这些配合物的浓度与每个PS II两个锰的总化学计量相对应时，可实现几乎完全的恢复；（c）双核锰配合物恢复的电子流在对添加50微摩尔乙二胺四乙酸（EDTA）的抗性方面与正常放氧的PS II制剂非常相似，而在相同螯合剂浓度下，氯化锰支持的电子流几乎被完全抑制。氧气释放速率被用作衡量在重建放氧能力中作为锰源发挥作用的能力的指标。发现：（i）与PS II电子传输的情况一样，合成双核锰配合物比氯化锰显著更有效；（ii）就锰浓度而言，在与每个PS II四个锰相对应的浓度下，μ-氧桥联双核锰（III）配合物（以M-3表示）可达到最大效果；（iii）在双核锰配合物M-3的所有浓度下，如果重建试验中还包含外在调节性33 kDa蛋白（PS II-O蛋白），则氧气释放速率的恢复会显著更高。（摘要截短于250字）
