Rotational Mechanism of F_1-ATPase : Crucial Importance of Water-Entropy Effect
Rotational Mechanism of F_1-ATPase : Crucial Importance of Water-Entropy Effect
复制标题
F_1-ATP酶的旋转机制：水熵效应的至关重要
DOI：
10.1021/ja109594y
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发表时间：
2011
影响因子：
15
通讯作者：
M.Kinoshita
中科院分区：
文献类型：
--
作者：
T.Yoshidome;Y.Ito;M.Ikeguchi;M.Kinoshita
We propose a novel picture of the rotation mechanism of F1-ATPase, a rotary-motor protein complex. Entropy, which originates from the translational displacement of water molecules, is treated as the key factor in the proposal. We calculate the water entropy gains upon formation of the α−β, α−γ, and β−γ subunit pairs. The gain is given as the difference between the hydration entropy of a subunit pair and the sum of the hydration entropies of the separate subunits forming the pair. The calculation is made using a hybrid of a statistical-mechanical theory for molecular liquids and morphometric approach. The water entropy gain is considered as a measure of tightness of the packing at each subunit interface. The results are highly correlated with the numbers of stable contacts at the subunit interfaces estimated by a molecular dynamics simulation. We also calculate the hydration entropies of three different subcomplexes comprising the γ subunit, one of the β subunits, and two α subunits adjacent to them. The major finding is that the packing in F1-ATPase is highly asymmetrical, and this asymmetry is ascribed to the water entropy effect. We discuss how the rotation of the γ subunit is induced by such chemical processes as ATP binding, ATP hydrolysis, and release of the products. In our picture, the asymmetrical packing plays crucially important roles, and the rotation is driven by the water entropy effect.
