Ion channels of alamethicin dimer N-terminally linked by disulfide bond
Ion channels of alamethicin dimer N-terminally linked by disulfide bond
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DOI：
10.1016/s0006-3495(03)74472-5
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发表时间：
2003-07-01
影响因子：
3.4
通讯作者：
Asami, K
中科院分区：
文献类型：
--
作者：
Okazaki, T;Sakoh, M;Asami, K
用二硫键连接n端，合成了一种共价的alamethicin Rf30二聚体。当二聚肽加入到二植烷酰PC膜的顺式侧时，宏观通道电流仅在顺式正电压下产生。单通道记录显示几个电导水平交替稳定。这些结果表明，二聚肽通过像alamethicin一样的n端插入形成稳定的通道，并且大多数孔是由偶数螺旋组装而成的。利用晚餐肽通道的长开放时间，通过在开放状态下施加快速电压坡道获得单通道的电流-电压（I-V）关系。I-V关系表现为整流，顺侧向横侧的电流大于反方向的电流。这种内在整流主要归因于围绕中心孔的平行肽螺旋的宏观偶极子。
A covalent dimer of alamethicin Rf30 was synthesized by linking the N-termini by a disulfide bond. When the dimer peptides were added to the cis-side of a diphytanoyl PC membrane, macroscopic channel current was induced only at cis positive voltages. The single-channel recordings showed several conductance levels that were alternately stabilized. These results indicate that the dimer peptides form stable channels by N-terminal insertion like alamethicin and that most of the pores are assembled from even numbers of helices. Taking advantages of the long open duration of the dinner peptide channels, the current-voltage (I-V) relations of the single-channels were obtained by applying fast voltage ramps during the open states. The I-V relations showed rectification, such that current from the cis-side toward the trans-side is larger than that in the opposite direction. The intrinsic rectification is mainly attributed to the macro dipoles of parallel peptide helices surrounding a central pore.