Distribution of ion pairs into a bilayer lipid membrane and its effect on the ionic permeability
Distribution of ion pairs into a bilayer lipid membrane and its effect on the ionic permeability
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离子对在双层脂膜中的分布及其对离子渗透性的影响
DOI：
10.1016/j.bbamem.2021.183724
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Yumi Yoshida
中科院分区：
文献类型：
--
作者：
Terumasa Omatsu;Kisho Hori;Naoto Ishida;Kohji Maeda;Yumi Yoshida
本文报道了目标离子和反离子在水相和人工双层类脂膜之间的分配常数及其对离子透过双层类脂膜的影响。还提出了基于目标离子和反离子分布的离子透过膜的理论公式，并通过分析反离子存在时荧光阳离子[罗丹明6G(R6G+)]通过膜的通量进行了验证(X−=1Br4−、BF4−和ClO4−)。通过同时测量跨膜电流密度和跨膜荧光强度作为膜电位的函数来评估跨膜通量。用脂质体萃取法测定了R6G+和X-−在水相和博莱姆相间的分配常数。测得的离子渗透率与R6G+或X−的浓度呈非线性关系，但与膜内R6G+和X−的浓度成正比，由R6G+和X−的分布常数估算。这一比例关系表明，阳离子和阴离子在水相和膜相之间的分布决定了离子在膜中的传输通量。所提出的公式可以表达跨膜电流与膜电位以及水相中R6G+和X-−浓度的关系。
This work reports the distribution constant of a target ion and a counter-ion between an aqueous phase and an artificial bilayer lipid membrane (BLM) and its influence to the ionic permeability through a BLM. A theoretical formula for ionic permeability through a BLM based on the distribution of the target ion and the counter-ion is also proposed and validated by analyzing the flux of a fluorescent cation [rhodamine 6G (R6G+)] through the BLM in the presence of counter-ions (X−= Br−, BF4−, and ClO4−). The transmembrane flux was evaluated by simultaneous measurement of the transmembrane current density and the transmembrane fluorescence intensity as a function of the membrane potential. The distribution constant of R6G+and X−between the aqueous and BLM phases was determined by a liposome-extraction method. The measured ionic permeability exhibited non-linear dependent on the aqueous concentration of R6G+or X−, but proportional to the concentration of R6G+and X−inside the BLM evaluated from the distribution constant of R6G+and X−. The proportionality demonstrates that the distribution of cations and anions between the aqueous and BLM phases dominates the flux of ion transport through the BLM. The proposed formula can express the dependence of the transmembrane current on the membrane potential and the concentrations of R6G+and X−in the aqueous phase.