Ono T, Nakayama H, Gleiter H, Inoue Y, Kawamori A
Arch Biochem Biophys. 1987 Aug 1;256(2):618-24. doi: 10.1016/0003-9861(87)90619-9.
Properties of the S2 state formed in photosystem II membranes in which Cl- had been replaced by various anions were investigated by means of thermoluminescence measurements and low temperature EPR spectroscopy. The Br--substituted membranes showed the normal thermoluminescence B-band arising from S2Q-B charge recombination, whereas the SO2-4-, F--, CH3COO--, and NO-3-substituted membranes showed modified B-bands with variously upshifted peak temperatures. The extent of the peak temperature upshift varied in parallel with the extent of inhibition of O2 evolution depending on the anion species. A normal EPR S2 multiline signal was induced in Br--substituted membranes, but its amplitude was reduced to less than 10% in F--, NO-3-, CH3COO--, and SO2-4-substituted membranes, In contrast, the g = 4.1 signal from S2 was markedly enhanced in F-- and NO-3-substituted membranes, not much affected in CH3COO-- and SO2-4-substituted membranes, and decreased to 70% in Br--substituted membranes. Based on these data, the effect of various types of S2 modification on the O2-evolving activity was discussed. It was suggested that anions have an important role in regulating the interaction between the Mn atoms, and thereby adjust the redox properties of the S2 state to enable further transitions beyond S2.
通过热释光测量和低温电子顺磁共振光谱，研究了用各种阴离子取代氯离子的光系统II膜中形成的S2态的性质。用溴离子取代的膜表现出由S2Q-B电荷复合产生的正常热释光B带，而用硫酸根离子、氟离子、醋酸根离子和硝酸根离子取代的膜表现出峰温度不同程度上移的改性B带。峰温度上移的程度与取决于阴离子种类的氧气释放抑制程度平行变化。在溴离子取代的膜中诱导出正常的电子顺磁共振S2多线信号，但在氟离子、硝酸根离子、醋酸根离子和硫酸根离子取代的膜中其幅度降低到小于10%。相反，来自S2的g = 4.1信号在氟离子和硝酸根离子取代的膜中显著增强，在醋酸根离子和硫酸根离子取代的膜中受影响不大，在溴离子取代的膜中降低到70%。基于这些数据，讨论了各种类型的S2修饰对氧气释放活性的影响。有人提出，阴离子在调节锰原子之间的相互作用中起重要作用，从而调整S2态的氧化还原性质，以便能够进行超越S2的进一步转变。
