Thermodynamic efficiency and mechanochemical coupling of F1-ATPase
Thermodynamic efficiency and mechanochemical coupling of F1-ATPase
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DOI：
10.1073/pnas.1106787108
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发表时间：
2011-11-01
影响因子：
11.1
通讯作者：
Muneyuki, Eiro
中科院分区：
文献类型：
--
作者：
Toyabe, Shoichi;Watanabe-Nakayama, Takahiro;Muneyuki, Eiro
F-1-ATPase 是一种纳米级生物能量转换器，作为 FoF1-ATP 合酶的一部分。其旋转机械在化学自由能和机械功之间转换能量，并通过合成几乎所有生物体中的大多数 ATP，在细胞能量转换中发挥核心作用。然而，与反应方案相比，有关其能量学的信息有限。事实上，诸如 F-1-ATP 酶如何有效地转换自由能等基本问题仍未得到解答。在这里，我们通过精确控制 ATP 水解的外部扭矩和化学势作为 FoF1-ATP 合酶的模型系统，证明了分离的 F-1-ATP 酶以离散的 120 度步骤可逆旋转。我们发现，F-1-ATPase 每 120 度步长执行的最大功几乎等于在多种条件下从单次 ATP 水解中提取的热力学最大功。我们的结果表明 F-1-ATP 酶具有 100% 的自由能转导效率和紧密的机械化学耦合。
F-1-ATPase is a nanosized biological energy transducer working as part of FoF1-ATP synthase. Its rotary machinery transduces energy between chemical free energy and mechanical work and plays a central role in the cellular energy transduction by synthesizing most ATP in virtually all organisms. However, information about its energetics is limited compared to that of the reaction scheme. Actually, fundamental questions such as how efficiently F-1-ATPase transduces free energy remain unanswered. Here, we demonstrated reversible rotations of isolated F-1-ATPase in discrete 120 degrees steps by precisely controlling both the external torque and the chemical potential of ATP hydrolysis as a model system of FoF1-ATP synthase. We found that the maximum work performed by F-1-ATPase per 120 degrees step is nearly equal to the thermodynamical maximum work that can be extracted from a single ATP hydrolysis under a broad range of conditions. Our results suggested a 100% free-energy transduction efficiency and a tight mechanochemical coupling of F-1-ATPase.