The mechanism of stimulation of photophosphorylation by amines and by nigericin
The mechanism of stimulation of photophosphorylation by amines and by nigericin
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DOI：
10.1016/0005-2728(88)90115-6
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发表时间：
1988-06
期刊：
影响因子：
--
通讯作者：
U. Pick;M. Weiss
中科院分区：
文献类型：
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作者：
U. Pick;M. Weiss
低浓度的尼日利亚菌素和水酚胺对光磷酸化的异常刺激已被重新研究。结果表明，这种刺激：(1)与糖对电子传递的抑制作用密切相关，而这种抑制作用被尼日利亚菌素和胺所逆转。糖抑制和尼日利亚菌素（或胺）刺激都涉及ATP 2 e -比值的微小变化。(2)受高盐抑制。(3)取决于氯化物的存在。(4)与ΔpH略有下降，Δψ略有上升和Δ\ 1 gm H+总体略有下降相关。光磷酸化的刺激与Δψ之间没有相关性，提示两者的作用是不相关的。(5)被低浓度的棕榈酸和gramicidin D阻断，它们抑制ATP的形成，但不影响Δ\ \ n gm H+（解耦合）。(6)糖和尼日利亚菌素或胺的最大效应是在两种光系统的电子传递驱动ATP形成时获得的，仅在光系统I工作时获得部分效应，而仅在光系统II工作时几乎没有任何效应。这些结果表明，尼日利亚菌素或胺对光磷酸化的刺激是由于盐的积累影响了电子传递以及ATP形成和电子传递之间的耦合。外部糖和内部高盐的条件可能诱导类囊体膜从体积-体积Δ\ \ n gm H+转变为局部H+偶联，这可能反映了膜内质子在电子传递和ATP合酶复合物之间的转移。
The anomalous stimulation of photophosphorylation by low concentrations of nigericin and hydrophylic amines has been reinvestigated. It is demonstrated that this stimulation is:(1) Closely linked to an inhibitory effect of sugars on electron transport which is reversed by nigericin and amines. Both sugar inhibition and nigericin (or amine) stimulation involve minor changes in ATP 2 e− ratios.(2) Inhibited by high salt.(3) Dependent on the presence of chloride.(4) Associated with a slight decrease in ΔpH, a slight increase in Δψ and an overall minor decrease in Δ\̃ gm H+. There is no correlation between the stimulation of photophosphorylation and Δψ, suggesting that the two effects are unrelated.(5) Blocked by low concentrations of palmitic acid and gramicidin D which inhibit ATP formation without affecting Δ\̃ gm H+(decoupling).(6) Maximal effects of sugars and nigericin or amines are obtained when ATP formation is driven by electron transport through both photosystems, partial effects are obtained when only Photosystem I is operative, while hardly any effects are obtained when only Photosystem II is operative. These results suggest that the stimulation of photophosphorylation by nigericin or amines results from salt accumulation which affects electron transport and the coupling between ATP formation and electron transport. Conditions of external sugar and internal high salt may induce in thylakoid membranes a shift from bulk-bulk Δ\̃ gm H+ to localized H+ coupling, probably reflecting intramembranal proton transfers between electron transport and ATP synthase complexes.