Water permeability of gramicidin A-treated lipid bilayer membranes.
Water permeability of gramicidin A-treated lipid bilayer membranes.
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DOI：
10.1085/jgp.72.3.341
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发表时间：
1978-09
期刊：
影响因子：
--
通讯作者：
Finkelstein A
中科院分区：
文献类型：
--
作者：
Rosenberg PA;Finkelstein A
在含有含水孔（通道）的膜中，渗透水渗透系数Pf大于扩散水渗透系数Pd。实际上，Pf/Pd的大小通常用于确定孔隙半径。虽然，对于迄今为止研究的膜，P f/P d随着孔半径的减小而单调下降，但当半径如此之小以至于水分子不能在通道内相互超越（单列传输）时，理论上假设的值存在争议。在一种观点中，它应该等于1，而在另一种观点中，它应该等于N，即孔隙中水分子的数量。短杆菌肽A在脂质双层膜中形成狭窄的水通道，通过该水通道可以进行单行运输。对于这些通道，我们发现P f/P d约为5。相比之下，对于较宽的制霉菌素和绿曲霉素B孔，Pf/Pd约为3。这些研究结果提供了实验支持的观点，P f/Pd = N的单行运输，因此，我们得出结论，有大约5个水分子短杆菌肽A通道。独立于流动电位数据得出了类似的结论。使用单通道电导数据，我们计算了单个短杆菌肽A通道的水渗透性。在附录中，我们报告了含胆固醇的膜中存在多种通道尺寸和寿命。
In membranes containing aqueous pores (channels), the osmotic water permeability coefficient, P f, is greater than the diffusive water permeability coefficient, P d. In fact, the magnitude of P f/P d is commonly used to determine pore radius. Although, for membranes studied to date, P f/P d monotonically declines with decreasing pore radius, there is controversy over the value it theoretically assumes when that radius is so small that water molecules cannot overtake one another within the channel (single-file transport). In one view it should equal 1, and in another view it should equal N, the number of water molecules in the pore. Gramicidin A forms, in lipid bilayer membranes, narrow aqueous channels through which single-file transport may occur. For these channels we find that P f/P d approximately 5. In contrast, for the wider nystatin and amphotericin B pores, P f/P d approximately 3. These findings offer experimental support for the view that P f/P d = N for single-file transport, and we therefore conclude that there are approximately five water molecules in a gramicidin A channel. A similar conclusion was reached independently from streaming potential data. Using single-channel conductance data, we calculate the water permeability of an individual gramicidin A channel. In the Appendix we report that there is a wide range of channel sizes and lifetimes in cholesterol-containing membranes.
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DOI：
10.1085/jgp.43.3.523
发表时间：
1960-01
期刊：
The Journal of general physiology
影响因子：
--
作者：
ROBBINS E;MAURO A
通讯作者：
MAURO A
影响因子：
3.8
作者：
HOLZ, R
通讯作者：
HOLZ, R
影响因子：
--
作者：
GRANTHAM, JJ;BURG, MB
通讯作者：
BURG, MB
DOI：
10.1085/jgp.72.3.327
发表时间：
1978-09
期刊：
The Journal of general physiology
影响因子：
--
作者：
Rosenberg PA;Finkelstein A
通讯作者：
Finkelstein A
DOI：
10.1016/s0065-2296(08)60183-4
发表时间：
1963-01-01
期刊：
ADVAN BOT RES
影响因子：
--
作者：
DAINTY, JACK
通讯作者：
DAINTY, JACK