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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Protein folding is slaved to solvent motions
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Protein folding is slaved to solvent motions

机译：蛋白质折叠作用于溶剂运动

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Proteins, the workhorses of living systems, are constructed from chains of amino acids, which are synthesized in the cell based on the instructions of the genetic code and then folded into working proteins. The time for folding varies from microseconds to hours. What controls the folding rate is hotly debated. We postulate here that folding has the same temperature dependence as the a-fluctuations in the bulk solvent but is much slower. We call this behavior slaving. Slaving has been observed in folded proteins: Large-scale protein motions follow the solvent fluctuations with rate coefficient k(alpha) but can be slower by a large factor. Slowing occurs because large-scale motions proceed in many small steps, each determined by k(alpha). if conformational motions of folded proteins are slaved, so a fortiori must be the motions during folding. The unfolded protein makes a Brownian walk in the conformational space to the folded structure, with each step controlled by k(alpha). Because the number of conformational substates in the unfolded protein is extremely large, the folding rate coefficient, k(f), is much smaller than k(alpha). The slaving model implies that the activation enthalpy of folding is dominated by the solvent, whereas the number of steps n(f) = k(alpha)/k(f) is controlled by the number of accessible substates in the unfolded protein and the solvent. Proteins, however, undergo not only alpha- but also beta-fluctuations. These additional fluctuations are local protein motions that are essentially independent of the bulk solvent fluctuations and may be relevant at late stages of folding.
机译：蛋白质是生命系统的主力，由氨基酸链构成，这些氨基酸链是根据遗传密码的指示在细胞中合成的，然后折叠成有效的蛋白质。折叠时间从微秒到几小时不等。控制折叠率的因素引起了激烈的争论。我们在这里假设折叠与本体溶剂中的a波动具有相同的温度依赖性，但速度要慢得多。我们称这种行为为奴隶。在折叠的蛋白质中观察到了奴隶现象：蛋白质的大规模运动遵循溶剂波动，速率系数为kα，但可能会大大降低。之所以会出现减速，是因为大规模运动以许多小步长进行，每个步长均由kα确定。如果折叠蛋白的构象运动是从动的，那么折叠过程中的运动必定是最重要的。展开的蛋白质在构象空间中向折叠结构进行布朗运动，每一步都由kα控制。由于未折叠蛋白质中构象亚状态的数量非常多，因此折叠率系数k（f）远小于kα。从模型表明，折叠的活化焓受溶剂支配，而步数n（f）=kα/ k（f）由未折叠的蛋白质和溶剂中可及的亚状态数控制。然而，蛋白质不仅会经历α-波动，而且还会经历β-波动。这些额外的起伏是局部蛋白质运动，其基本独立于整体溶剂起伏，并且可能在折叠后期有关。

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