TRANSPORT MECHANISM OF HYDROPHOBIC IONS THROUGH LIPID BILAYER MEMBRANES
TRANSPORT MECHANISM OF HYDROPHOBIC IONS THROUGH LIPID BILAYER MEMBRANES
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DOI：
10.1007/bf01870551
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发表时间：
1971-01-01
影响因子：
2.4
通讯作者：
LAUGER, P
中科院分区：
文献类型：
--
作者：
KETTERER, B;NEUMCKE, B;LAUGER, P
有证据表明，脂溶离子通过双层膜的传输分三个不同的步骤进行：(1)吸附到膜-溶液界面；(2)越过活化势垒到达相反的界面；(3)解吸到水溶液中。对这一机制的支持来自于对离子势能的考虑，离子势能在界面上具有最小值。模型的形式分析表明，各个输运步骤的速率常数可以由电压突变后电流的松弛来确定。以二苦胺和四苯基硼为渗透性离子进行了这种松弛实验。在这两种情况下，速率决定步骤是从吸附位置到水相的跳跃。此外，还发现随着离子浓度的增加，膜电导出现一个极大值。根据L.J.Bruner最近发展的模型，这种行为是由界面饱和来解释的，这导致了高浓度时电导的阻塞。
Evidence is presented that the transport of lipid-soluble ions through bilayer membranes occurs in three distinct steps: (1) adsorption to the membranesolution interface; (2) passage over an activation barrier to the opposite interface; and (3) desorption into the aqueous solution. Support for this mechanism comes from a consideration of the potential energy of the ion, which has a minimum in the interface. The formal analysis of the model shows that the rate constants of the individual transport steps can be determined from the relaxation of the electric current after a sudden change in the voltage. Such relaxation experiments have been carried out with dipicrylamine and tetraphenylborate as permeable ions. In both cases the rate-determining step is the jump from the adsorption site into the aqueous phase. Furthermore, it has been found that with increasing ion concentration the membrane conductance goes through a maximum. In accordance with the model recently developed by L. J. Bruner, this behavior is explained by a saturation of the interface, which leads to a blocking of the conductance at high concentrations.