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Whole-cell Patch-clamp Recordings for Electrophysiological Determination of Ion Selectivity in Channelrhodopsins
Published on: May 22, 2017
An Artificial Single Molecular Channel Showing High Chloride Transport Selectivity and pH-Responsive Conductance
Wen-Long Huang1, Xu-Dong Wang1, Yu-Fei Ao1,2
1Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Abstract:
Inspired by the unique structure and function of the natural chloride channel (ClC) selectivity filter, we present herein the design of a ClC-type single channel molecule. This channel displays high ion transport activity with half-maximal effective concentration, EC50 , of 0.10 μM, or 0.075 mol % (channel molecule to lipid ratio), as determined by fluorescent analysis using lucigenin-encapsulated vesicles. Planar bilayer lipid membrane conductance measurements indicated an excellent Cl- /K+ selectivity with a permeability ratio P /P up to 12.31, which is comparable with the chloride selectivity of natural ClC proteins. Moreover, high anion/anion selectivity (P /P =66.21) and pH-dependent conductance and ion selectivity of the channel molecule were revealed. The ClC-like transport behavior is contributed by the cooperation of hydrogen bonding and anion-π interactions in the central macrocyclic skeleton, and by the existence of pH-responsive terminal phenylalanine residues.
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