Dimroth P, Kaim G, Matthey U
Institut für Mikrobiologie, Eidgenössische Technische Hochschule, ETH-Zentrum, Schmelzbergstrasse 7, CH-8092 Zürich, Switzerland.
J Exp Biol. 2000 Jan;203(Pt 1):51-9. doi: 10.1242/jeb.203.1.51.
ATP, the universal carrier of cell energy, is manufactured from ADP and phosphate by the enzyme ATP synthase using the free energy of an electrochemical gradient of protons (or Na(+)). The proton-motive force consists of two components, the transmembrane proton concentration gradient (delta pH) and the membrane potential. The two components were considered to be not only thermodynamically but also kinetically equivalent, since the chloroplast ATP synthase appeared to operate on delta pH only. Recent experiments demonstrate, however, that the chloroplast ATP synthase, like those of mitochondria and bacteria, requires a membrane potential for ATP synthesis. Hence, the membrane potential and proton gradient are not equivalent under normal operating conditions far from equilibrium. These conclusions are corroborated by the finding that only the membrane potential induces a rotary torque that drives the counter-rotation of the a and c subunits in the F(o) motor of Propionigenium modestum ATP synthase.
三磷酸腺苷（ATP）是细胞能量的通用载体，由二磷酸腺苷（ADP）和磷酸通过ATP合酶利用质子（或Na⁺）电化学梯度的自由能合成。质子动力由两个成分组成，即跨膜质子浓度梯度（ΔpH）和膜电位。这两个成分不仅在热力学上，而且在动力学上都被认为是等效的，因为叶绿体ATP合酶似乎仅作用于ΔpH。然而，最近的实验表明，叶绿体ATP合酶与线粒体和细菌的ATP合酶一样，ATP合成需要膜电位。因此，在远离平衡的正常操作条件下，膜电位和质子梯度并不等效。丙酸栖热栖热菌ATP合酶F₀马达中的a和c亚基反向旋转是由膜电位诱导的旋转扭矩驱动的，这一发现证实了这些结论。
