Asymmetry in the F1-ATPase and its implications for the rotational cycle.
Asymmetry in the F1-ATPase and its implications for the rotational cycle.
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F1-ATP 酶的不对称性及其对旋转周期的影响。
DOI：
10.1016/s0006-3495(04)74208-3
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Oster,George
中科院分区：
文献类型：
--
作者：
Sun,SeanX;Wang,Hongyun;Oster,George
ATP合成酶使用旋转机制来执行其制造ATP的细胞功能。中心γ轴在由交替的α和β亚基组成的六聚体圆柱体内旋转。当在高摩擦负荷和低ATP浓度下以水解方向操作时，β亚基的三个催化位点中的协调机械化学循环以三个120°步骤旋转γ轴。在低摩擦载荷下，120°台阶与三个ATP独立的子台阶交替，间隔约30°。我们提出了一个定量模型，占这些子步骤，并表明所观察到的暂停是由于1），F1六聚体的不对称性，产生了动力冲程的螺旋桨状运动和2），ADP的催化位点的相对紧密的结合。
ATP synthase uses a rotary mechanism to carry out its cellular function of manufacturing ATP. The centralγ-shaft rotates inside a hexameric cylinder composed of alternatingα- andβ-subunits. When operating in the hydrolysis direction under high frictional loads and low ATP concentrations, a coordinated mechanochemical cycle in the three catalytic sites of theβ-subunits rotates theγ-shaft in three 120° steps. At low frictional loads, the 120° steps alternate with three ATP-independent substeps separated by ∼30°. We present a quantitative model that accounts for these substeps and show that the observed pauses are due to 1), the asymmetry of the F1hexamer that produces a propeller-like motion of the power-stroke and 2), the relatively tight binding of ADP to the catalytic sites.