Maloney P C
J Membr Biol. 1982;67(1):1-12. doi: 10.1007/BF01868643.
This review summarizes recent work on energy coupling to ATP synthesis by the reversible, proton-translocating ATPase to mitochondria, chloroplasts, and bacteria. In the first sections, this enzyme is distinguished from other ATP-linked ion transport systems, and progress in the biochemical analysis is discussed. There is at present a reasonably consistent idea of the overall structure of the enzyme, and one can begin to assign specific functional roles to individual subunits of the complex. The latter half of the review deals with mechanisms of energy coupling, about which there is clear divergence of opinion. An "indirect coupling" model would allow for the possibility that H+ translocation transmits energy for ATP synthesis by driving the enzyme through a sequence of conformational states, so that H+ translocated need not take part in the chemistry of ATP synthesis. By contrast, a "direct coupling" mechanism would specify that H+ translocated must participate in the chemical reaction by combining with oxygen must participate in the chemical reaction by combining with oxygen from phosphate during the synthetic step. Such discussion is preceded by an outlined of the "proton well," since this idea forms the basis of one direct coupling model. In addition, it is suggested that the idea of a proton (ion) well may be of more general significance to the analysis of ion-coupled transport, because it includes the postulate that mechanistically significant ion binding can occur within the profile of the electric field. A proton (ion) well can be derived from both kinetic and equilibrium treatments, and from mechanistic considerations in fields as distinct as biochemistry and neurophysiology. As a result, it illustrates how further advances in formulating mechanisms of energy coupling might profit by a merger of technique and perspective from areas that have as a common goal an understanding of how large proteins catalyze movements of small molecules across a membrane.
本综述总结了关于可逆性质子转运ATP酶与线粒体、叶绿体和细菌的ATP合成之间能量偶联的近期研究工作。在开头部分，将这种酶与其他与ATP相关的离子转运系统进行了区分，并讨论了生化分析方面的进展。目前对于该酶的整体结构已有较为一致的认识，人们可以开始为该复合物的各个亚基赋予特定的功能角色。综述的后半部分讨论了能量偶联机制，对此存在明显的意见分歧。“间接偶联”模型认为，H⁺转运通过驱动酶经历一系列构象状态来传递用于ATP合成的能量，这样转运的H⁺无需参与ATP合成的化学反应。相比之下，“直接偶联”机制则明确指出，转运的H⁺必须在合成步骤中与来自磷酸的氧结合参与化学反应。在进行此类讨论之前，先概述了“质子阱”，因为这一概念构成了一种直接偶联模型的基础。此外，有人提出质子（离子）阱的概念对于离子偶联转运的分析可能具有更普遍的意义，因为它包含了这样一种假设，即在电场分布范围内可能发生具有重要机制意义的离子结合。质子（离子）阱可以从动力学和平衡处理以及生物化学和神经生理学等不同领域的机制考虑中推导出来。因此，它说明了在阐述能量偶联机制方面的进一步进展如何可能通过融合不同领域的技术和观点而受益，这些领域的共同目标是理解大蛋白质如何催化小分子跨膜移动。
