Abstract:

Characterization of energy-transduction on the chloroplast thylakoid membranes from spinach (Spinacia oleracea L.) after thermal pretreatment was investigated. The related reactions of energy-transduction in chloroplasts were seriously affected by thermal pretreatment. The results were obtained as following: (1) The rate of cyclic photophosphorylation declined when the pretreatment temperature increased in the range of 25 to 45 ℃. (2) The thermal pretreatment led to a decrease of the activity of thylakoid membrane-bounded ATPase. (3) Proton uptake of chloroplasts and the fluorescence quenching of 9-aminoacridine (9-AA) in thylakoid membrane decreased after the thermal pretreatment, but addition of dicyclohexylcarbodiimide (DCCD) could partially restore the fluorescence quenching of 9-AA. (4) Both the rates of fast phase in electrochroism absorption change at 515 nm and the millisecond delayed light emission (ms-DLE) of chloroplast showed a progressive decrease upon raising the temperature of pretreatment. (5) Immunbloting analysis showed that the thermal pretreatment caused the changes of protein content and the electrophoresis mobility of thylakoid membrane-bound ATPase and its α-subunit. (6) If the temperature of pretreatment were higher than 33 ℃, oxygen uptake of PSⅠ -mediated in the samples was rapidly inhibited, but addition of sinapine into the reaction medium could partially restore the ability of oxygen uptake in the samples. These results are briefly discussed in relation to the change of permeability of thylakoid membranes, the dissociation of coupling factor complex as well as accumulation of the radicals in the thylakoid membranes after thermal pretreatment.

热预处理菠菜叶绿体的能量转换特征
彭建新¹万常照²邹永龙¹ 陈根云¹ 钱月琴¹ 袁勤²王国强^1*

（1. 中国科学院上海植物生理研究所，上海200032；2. 上海市农业科学研究院作物研究所，上海201160）

墒要: 经热预处理（温度为25～45 ℃，部分实验为20～36 ℃，时间为5～10 min）的菠菜(Spinacia oleracea L.)叶绿体，严重影响其能量转换的各步反应。⑴循环光合磷酸化速率随处理温度增高而下降。⑵类囊体膜上腺三磷酶失活。⑶光照诱导叶绿体的质子吸收减小；叶绿体的9_氨基吖啶（9_AA）荧光猝灭减弱，但加二环己基碳二亚胺(DCCD)可以部分恢复9_AA荧光猝灭。⑷叶绿体的延迟发光和ΔA515 nm电色效应均出现明显变化。⑸免疫印迹反应结果表明，经45 ℃预处理叶绿体的膜上腺三磷酶出现解离，其α亚单位的蛋白量明显减少。⑹预处理温度超过33 ℃，叶绿体光系统Ⅰ介导的氧吸收速率也下降，在反应介质中加芥子碱可以部分恢复其氧吸收能力。就这些结果与膜透性变化、耦联因子复合物解离和自由基积累的关系进行了讨论。

关键词： 菠菜；叶绿体；热预处理；能量转换；类囊体膜透性；耦联因子复合物

Key words: Spinacia oleracea, chloroplast, thermal pretreatment, energy-transduction, permeability of thylakoid membranes, coupling factor complex