Lazár Dusan, Ilík Petr, Kruk Jerzy, Strzałka Kazimierz, Naus Jan
Laboratory of Biophysics, Department of Experimental Physics, Faculty of Science, Palacký University, tr. Svobody 26, 771 46 Olomouc, Czech Republic.
J Theor Biol. 2005 Mar 21;233(2):287-300. doi: 10.1016/j.jtbi.2004.10.015. Epub 2004 Dec 1.
In this work, we extended the reversible radical pair model which describes energy utilization and electron transfer up to the first quinone electron acceptor (Q(A)) in photosystem II (PSII), by redox reactions involving cytochrome (cyt) b559. In the model, cyt b559 accepts electrons from the reduced primary electron acceptor in PSII, pheophytin, and donates electrons to the oxidized primary electron donor in PSII (P680+). Theoretical simulations of chlorophyll fluorescence rise based on the model show that the maximal fluorescence, F(M), increases with an increasing amount of initially reduced cyt b559. In this work we applied, the first to our knowledge, metabolic control analysis (MCA) to a model of reactions in PSII. The MCA was used to determine to what extent the reactions occurring in the model control the F(M) level and how this control depends on the initial redox state of cyt b559. The simulations also revealed that increasing the amount of initially reduced cyt b559 could protect PSII against photoinhibition. Also experimental data, which might be used to validate our theory, are presented and discussed.
在这项工作中，我们扩展了可逆自由基对模型，该模型描述了光系统II（PSII）中直至第一个醌电子受体（Q(A)）的能量利用和电子转移，通过涉及细胞色素（cyt）b559的氧化还原反应来实现。在该模型中，细胞色素b559从PSII中还原的初级电子受体脱镁叶绿素接受电子，并将电子捐赠给PSII中氧化的初级电子供体（P680+）。基于该模型对叶绿素荧光上升的理论模拟表明，最大荧光F(M)随着初始还原的细胞色素b559数量的增加而增加。在这项工作中，据我们所知，我们首次将代谢控制分析（MCA）应用于PSII中的反应模型。MCA用于确定模型中发生的反应在何种程度上控制F(M)水平，以及这种控制如何依赖于细胞色素b559的初始氧化还原状态。模拟还表明，增加初始还原的细胞色素b559的数量可以保护PSII免受光抑制。此外，还展示并讨论了可能用于验证我们理论的实验数据。
