ATP synthesis by the F1Fo ATP synthase of Escherichia coli is obligatorily dependent on the electric potential
ATP synthesis by the F1Fo ATP synthase of Escherichia coli is obligatorily dependent on the electric potential
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大肠杆菌 F1Fo ATP 合酶的 ATP 合成必须依赖于电势
DOI：
10.1016/s0014-5793(98)00969-7
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发表时间：
1998
期刊：
影响因子：
3.5
通讯作者：
P. Dimroth
中科院分区：
文献类型：
--
作者：
G. Kaim;P. Dimroth
纯化大肠杆菌H+易位F1FoATP合成酶，重组成蛋白脂质体。当以琥珀酸盐、丙二酸盐或马来酸盐为酸/碱转换（pHin=5.0; pHout=8.3），而不以MES作为酸性缓冲液时，该体系催化ATP合成。在这些实验条件下，琥珀酸盐（可能是单阴离子）的扩散产生125-130 mV的电位，而在MES缓冲液中，测量的电位在背景水平（~ 5 mV）。通过K+/valinomycin扩散电位，在pH 7.2不含ΔpH的情况下也合成了ATP。ATP合成速率随电位呈指数增长，并在70 mV左右出现拐点。我们从这些结果中得出结论，ΔpH和ΔΨ是大肠杆菌ATP合酶合成ATP的动力学不相等的驱动力，ΔΨ是这种合成的强制性力量。讨论了这些发现对ATP合成机制的一般意义。
The H+-translocating F1FoATP synthase of Escherichia coli was purified and reconstituted into proteoliposomes. This system catalyzed ATP synthesis when energized by an acid/base transition (pHin=5.0; pHout=8.3) with succinate, malonate or maleinate but not with MES as the acidic buffer. Under these experimental conditions an electric potential of 125–130 mV is generated by the diffusion of succinate, probably the monoanionic species, whereas with MES buffer the measured potential was at background level (∼5 mV). ATP was also synthesized at pH 7.2 in the absence of a ΔpH by applying a K+/valinomycin diffusion potential. The rate of ATP synthesis increased with the potential in an exponential manner with an inflection point at about 70 mV. We conclude from these results that ΔpH and ΔΨ are kinetically unequivalent driving forces for ATP synthesis by the E. coli ATP synthase and that ΔΨ is a mandatory force for this synthesis. The significance of these findings for the mechanism of ATP synthesis in general is discussed.