Department of Plant Physiology, Wageningen Agricultural University, Arboretumlaan 4, 6703 BD, Wageningen, The Netherlands.
Photosynth Res. 1993 Aug;37(2):165-75. doi: 10.1007/BF02187475.
Silicomolybdate (SiMo) and its effects on thylakoids have been characterized to evaluate its use as a probe for Photosystem II (PS II). It can accept electrons at two places in the electron transport chain: one at PS II and the other at PS I. In the presence of 1 μM 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) only the site at PS II is available. It is suggested that SiMo must disp;ace bicarbonate from its binding site to be able to function as an electron acceptor. This displacement is non-competitive. The binding of SiMo is inhibited differentially by PS II inhibitors: dinoseb>ioxynil> diuron. This difference is determined by the different positions of the inhibitors within the QB binding niche and their interaction with bicarbonate. The experimental results show that the SiMo-binding niche is located between the parallel helices of the D1 and D2 proteins of PS II, close to the non-heme iron. We conclude that SiMo is an electron acceptor with unique characteristics useful as a probe of the acceptor side of PS II.
硅钼酸盐（SiMo）及其对类囊体的作用已被确定，以评估其作为光系统 II（PS II）探针的用途。它可以在电子传递链中的两个位置接受电子：一个在 PS II，另一个在 PS I。在存在 1 μM 2,5-二溴-3-甲基-6-异丙基-p-苯醌（DBMIB）的情况下，只有 PS II 处的位置可用。据推测，SiMo 必须从其结合部位置换出碳酸氢盐才能作为电子受体发挥作用。这种置换是非竞争性的。PS II 抑制剂对 SiMo 的结合具有不同的抑制作用：敌草隆>肟菌酯> 敌草净。这种差异取决于抑制剂在 QB 结合位的不同位置及其与碳酸氢盐的相互作用。实验结果表明，SiMo 结合位位于 PS II 的 D1 和 D2 蛋白的平行螺旋之间，靠近非血红素铁。我们得出结论，SiMo 是一种具有独特特性的电子受体，可用作 PS II 受体侧的探针。
