The loose coupling mechanism in molecular machines of living cells.
The loose coupling mechanism in molecular machines of living cells.
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DOI：
10.1016/0065-227x(86)90005-5
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发表时间：
1986-01-01
影响因子：
--
通讯作者：
Hayashi, S
中科院分区：
文献类型：
--
作者：
Oosawa, F;Hayashi, S
对于由质子通量驱动的细菌鞭毛马达，已经提出了一种松耦合机制，其中质子的运动与马达的旋转间接且松耦合。这种机制保证了质子的电和化学势能与热涨落的能量具有相同量级的有效和平滑的转换。质子ATP酶也被认为是松偶联的。质子流产生蛋白质分子的旋转运动，这种运动促进ATP的合成。在所提出的机制中，合成一个ATP分子所需的质子数不是整数，而是根据环境条件而变化。在肌肉的情况下，ATP的水解和缩短之间的耦合被发现是非常松散的。活细胞中的分子机器可能经常采用松散耦合机制，其中化学反应和物理循环并不总是明确的一一对应。
For a bacterial flagellar motor driven by a proton flux, a loose coupling mechanism has been proposed in which the movement of the proton is indirectly and loosely coupled with the rotation of the motor. This mechanism assures the efficient and smooth conversion of both electrical and chemical potential energies of the proton of the same order as the energy of the thermal fluctuation. Loose coupling has been also assumed for the proton ATPase. A proton flux produces a rotational movement of protein molecules and this movement promotes the synthesis of ATP. In the proposed mechanism, the number of protons necessary for the synthesis of one ATP molecule is not an integer but varies depending on the environmental condition. In the case of muscle, the coupling between the hydrolysis of ATP and the shortening was found to be extremely loose. It is likely that molecular machines in living cells often adopt a loose coupling mechanism in which the chemical reaction and the physical cycle have not always a definite one-to-one correspondence.