Ion exchange phase transitions in water-filled channels with charged walls.
Ion exchange phase transitions in water-filled channels with charged walls.
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带电荷壁的充满水的通道中的离子交换相变。
DOI：
10.1103/physreve.73.051205
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
B. Shklovskii
中科院分区：
文献类型：
--
作者：
J. Zhang;A. Kamenev;B. Shklovskii
通过狭窄的充水通道的离子传输受到高静电屏障的阻碍。后者源于水和周围介质的介电常数的大比率。我们表明，“兴奋剂”，即，附着在沟道壁上的不动电荷大大降低了势垒。这就解释了为什么大多数生物离子通道是“掺杂的”。“我们表明，在相当一般的条件下，通道可能会经历离子交换相变（通常是一级）。在这样的转变时，有限的潜在浓度的离子可以进入或离开通道，或者在不同价态的离子之间交换。我们讨论了这些转换的生物钙通道的钙与钠的选择性的可能影响。我们还表明，二价钙离子的运输是协助他们分成两个单独的激发。
Ion transport through narrow water-filled channels is impeded by a high electrostatic barrier. The latter originates from the large ratio of the dielectric constants of the water and the surrounding media. We show that "doping," i.e., immobile charges attached to the walls of the channel, substantially reduces the barrier. This explains why most of the biological ion channels are "doped." We show that at rather generic conditions the channels may undergo ion exchange phase transitions (typically of the first order). Upon such a transition a finite latent concentration of ions may either enter or leave the channel, or be exchanged between the ions of different valences. We discuss possible implications of these transitions for the Ca-vs-Na selectivity of biological Ca channels. We also show that transport of divalent Ca ions is assisted by their fractionalization into two separate excitations.
影响因子：
3.4
作者：
Aksimentiev, A;Heng, JB;Schulten, K
通讯作者：
Schulten, K