氯乙酸盐对PSⅡ和紫细菌反应中心电子传递不同影响的比较  

Comparison of Different Effects of Chioroacetates on Electron Transports in PSⅡ and in the Reaction Center of Rb. sphaeroides 601

作　　者：俞皓[1] 曾小华[2] 李坤宝[1] 宋鸿遇[2] 朱章玉[1] 徐春和[2] 

机构地区：[1]上海交通大学生物科学与技术系,200030 [2]中国科学院上海植物生理研究所,200032

出　　处：《生物化学与生物物理学报》1997年第1期53-60,共8页

基　　金：国家自然科学基金(39370007)资助项目

摘　　要：本工作比较了氯乙酸盐对紫细菌Rb.sphaeroides 601(RS601)光合作用反应中心和高等植物光系统Ⅱ电子传递的不同影响。利用双闪叶绿素α荧光测定PSⅡ还原侧电子传递的结果表明:低浓度氯乙酸盐对~Q_A^-→Q_B(Q_B^-)电子传递及Q_A^-Q_B(Q_B^-)←→Q_AQ_B^-(Q_B^(2-))的平衡有明显的抑制。氯乙酸盐对PSⅡ还原侧电子传递的抑制作用介于抑制电子传递和抑制质子转移两种方式之间。对PSⅡ氧化侧电子传递的研究表明氯乙酸盐在PSⅡ氧化侧尚有抑制位置。500mmol/L氯乙酸盐对RS601载色体中DCPIPH_2到MV电子传递无明显抑制。通过Dixon作图对细菌反应中心电子传递的分析表明,三氯乙酸盐的解离常数为∞,而OP的解离常数为1.1×10^(-3)mol/L。文章中从结构和功能上讨论了两种反应中心的异同。Chloroacetates displayed different effects on electron transports in the photosynthetic reaction center of purple bacteria(Rb, sphaeroides 601) and in the photosystem Ⅱ(PS Ⅱ) of higher plants. Decays of chlorophyll α fluorescence measured after actinic flashes show that chloroacetates inhibit the electron transport from Q_A^- to Q_B(Q_B^- ) and the equilibrium between Q_A^- Q_B(Q_B^- ) and Q_AQ_B^-(Q_B^(2-)), acting on electron transport as well as proton transduction. The study on PS Ⅱ electron transport indicates another inhibition site of chloroacetate at the oxidation side of PS Ⅱ. Chloroacetates up to 500 mM have no inhibition on the DCPIPH_2→MV electron transport in the RS601's chromatophores. Dissociation constants of OP and trichloroacetates from RS601 reaction center were assessed to be 1.1 ×10^(-3) M and ∞ from Dixon curve respectively. The differences on aspects of structures and functions between RS601 reaction center and PS Ⅱ were discussed.

关 键 词：光合作用 电子传递 氯乙酸盐 光系统Ⅱ 紫细菌 

分 类 号：Q945.11[生物学—植物学] Q939.107