Ultrasensitive liposome-based assay for the quantification of fundamental ion channel properties
Ultrasensitive liposome-based assay for the quantification of fundamental ion channel properties
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基于超灵敏脂质体的测定，用于定量基本离子通道特性
DOI：
10.1016/j.aca.2020.03.044
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发表时间：
2020-05-22
影响因子：
6.2
通讯作者：
Shao，Zhifeng
中科院分区：
文献类型：
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作者：
Shen，Yi;Zhong，Yulong;Shao，Zhifeng
表征通过纳米级合成或生物通道的跨膜离子转运的最广泛使用的方法之一是直接的基于脂质体的测定，其使用pH或离子敏感染料监测跨囊泡膜的离子通量的变化。然而，未能解释精确的实验条件，特别是膜两侧的完整离子组成和离子通过脂质双层本身的固有渗透性，可能会妨碍定量并导致根本错误的结论。在这里，我们提出了一个定量模型的基础上的Goldman-Hodgkin-Katz通量理论，这使得准确的测量和确定的最佳条件，离子通道的渗透性和选择性的测定。基于我们的模型，通道渗透率的检测灵敏度比通常使用的实验条件提高了两个数量级。此外，而不是获得定性偏好的离子选择性是典型的，我们确定这些参数的定量值在严格控制的条件下，即使实验结果会暗示（没有我们的模型）不正确的行为。我们预计，这种简单的超灵敏测定将发现广泛的应用在合成或生物离子通道的定量表征。
One of the most widely used approaches to characterize transmembrane ion transport through nanoscale synthetic or biological channels is a straightforward, liposome-based assay that monitors changes in ionic flux across the vesicle membrane using pH- or ion-sensitive dyes. However, failure to account for the precise experimental conditions, in particular the complete ionic composition on either side of the membrane and the inherent permeability of ions through the lipid bilayer itself, can prevent quantifications and lead to fundamentally incorrect conclusions. Here we present a quantitative model for this assay based on the Goldman–Hodgkin–Katz flux theory, which enables accurate measurements and identification of optimal conditions for the determination of ion channel permeability and selectivity. Based on our model, the detection sensitivity of channel permeability is improved by two orders of magnitude over the commonly used experimental conditions. Further, rather than obtaining qualitative preferences of ion selectivity as is typical, we determine quantitative values of these parameters under rigorously controlled conditions even when the experimental results would otherwise imply (without our model) incorrect behavior. We anticipate that this simply employed ultrasensitive assay will find wide application in the quantitative characterization of synthetic or biological ion channels.