EFFECTS OF INORGANIC-PHOSPHATE ON THE LIGHT DEPENDENT THYLAKOID ENERGIZATION OF INTACT SPINACH-CHLOROPLASTS
EFFECTS OF INORGANIC-PHOSPHATE ON THE LIGHT DEPENDENT THYLAKOID ENERGIZATION OF INTACT SPINACH-CHLOROPLASTS
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DOI：
10.1104/pp.91.1.221
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发表时间：
1989-09-01
期刊：
影响因子：
7.4
通讯作者：
HELDT, HW
中科院分区：
文献类型：
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作者：
HEINEKE, D;STITT, M;HELDT, HW
以离体完整菠菜（Spinacia oleracea L.）用不同浓度的无机磷酸盐（Pi）孵育叶绿体。使用了两种独立的方法：（a）[14 C] 5，5-二甲基-2，4-恶唑烷二酮和[14 C]甲胺的积累;（B）能量依赖性叶绿素荧光猝灭。抑制CO2固定的超最佳介质Pi或通过添加甘油三酸酯-一种抑制剂的卡尔文循环-导致增加的类囊体膜的渗透率;然而，膜渗透率降低时，叶绿体被抑制的次最佳Pi。这种特定的“低磷酸盐”效应可以通过加入草酰乙酸来部分逆转，草酰乙酸再生电子受体NADP+并刺激线性电子传递。然而，即使在草酰乙酸存在下，在低Pi中观察到的α总是低于超最佳Pi。在存在少量N，N“-二环己基碳二亚胺的情况下，能量恢复，所述碳二亚胺与包括偶联因子1 ATP合酶的质子通道反应。N，N“-二环己基碳二亚胺对超适Pi叶绿体的叶绿体色素合成没有影响。这些结果表明，有一个特定的“低磷酸”质子泄漏的类囊体，并讨论了其起源。
The light dependent energization of the thylakoid membrane was analyzed in isolated intact spinach (Spinacia oleracea L.) chloroplasts incubated with different concentrations of inorganic phosphate (Pi). Two independent methods were used: (a) the accumulation of [14C]5,5-dimethyl-2,4,-oxazolidinedione and [14C] methylamine; (b) the energy dependent chlorophyll fluorescence quenching. The inhibition of CO2 fixation by superoptimal medium Pi or by adding glyceraldehyde-an inhibitor of the Calvin cycle-leads to an increased energization of the thylakoid membrane; however, the membrane energization decreases when chloroplasts are inhibited by suboptimal Pi. This specific ''low phosphate'' effect could be partially reversed by adding oxaloacetate, which regenerates the electron acceptor NADP+ and stimulates linear electron transport. The energization seen in low Pi is, however, always lower than in superoptimal Pi, even in the presence of oxaloacetate. Energization recovers in the presence of low amounts of N,N''-dicyclohexylcarbodiimide, which reacts with proton channels including the coupling factor 1 ATP synthase. N,N''-Dicyclohexylcarbodiimide has no effect on energization of chloroplasts in superoptimal Pi. These results suggest there is a specific ''low phosphate'' proton leak in the thylakoids, and its origin is discussed.