The mitochondrial F₁F_O‐ATPase in the presence of the natural cofactor Mg²⁺ acts as the enzyme of life by synthesizing ATP, but it can also hydrolyze ATP to pump H⁺. Interestingly, Mg²⁺ can be replaced by Ca²⁺, but only to sustain ATP hydrolysis and not ATP synthesis. When Ca²⁺ inserts in F₁, the torque generation built by the chemomechanical coupling between F₁ and the rotating central stalk was reported as unable to drive the transmembrane H⁺ flux within F_O. However, the failed H⁺ translocation is not consistent with the oligomycin‐sensitivity of the Ca²⁺‐dependent F₁F_O‐ATP(hydrol)ase. New enzyme roles in mitochondrial energy transduction are suggested by recent advances. Accordingly, the structural F₁F_O‐ATPase distortion driven by ATP hydrolysis sustained by Ca²⁺ is consistent with the permeability transition pore signal propagation pathway. The Ca²⁺‐activated F₁F_O‐ATPase, by forming the pore, may contribute to dissipate the transmembrane H⁺ gradient created by the same enzyme complex.

中文翻译：

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Ca2+ 作为线粒体 H+ 转运 F1FO-ATP（水解）酶的辅助因子

在天然辅因子 Mg ²⁺存在下，线粒体 F ₁ F _O -ATPase通过合成 ATP 充当生命酶，但它也可以水解 ATP 以泵送 H ⁺。有趣的是，Mg ²⁺可以被Ca ²⁺替代，但只能维持ATP 水解而不是ATP 合成。当 Ca ²⁺插入 F _{1 时}，F ₁和旋转中心茎之间的化学机械耦合产生的扭矩被报告为无法驱动F _O内的跨膜 H ⁺通量。然而，失败的 H ⁺易位与 Ca ²⁺依赖性 F ₁ F _O -ATP(水解)酶的寡霉素敏感性不一致。最近的进展表明了酶在线粒体能量转导中的新作用。因此，由 Ca ²⁺维持的 ATP 水解驱动的结构 F ₁ F _O -ATPase 畸变与渗透性转变孔隙信号传播途径一致。Ca ²⁺激活的 F ₁ F _O -ATPase，通过形成孔，可能有助于消散由相同酶复合物产生的跨膜 H ⁺梯度。