A Non‐Peptidic Ion Channel with K⁺ Selectivity

Abstract

The resorcinol–octadecanal cyclotetramer 1 forms an ion channel in planar lipid bilayers. A stable conductance level is observed with well‐defined transitions between open and closed states. The channel discriminates K+ from Na+ ions as well as cations from anions (for example, K+ from Cl−), as indicated by permeability ratios of 3 and 20, respectively. Rb+ ions block the K+ ion current.

An artificial sodium ion channel from calix[4]arene in the 1,3-alternate conformation

“…Rigid macrocycles have also been employed in cation channel mimetic compounds. Resorcin [4]arenes with undecyl and heptadecyl substituents conduct both Na + and K + , with selectivity for K + over Na + by a factor of three, but only for derivatives with the longer substituents [20]. Similar results were reported for other resorcin [4]arenes [21] but calixarenes, in particular calix [4]arene, have latterly been seen as potential ion selective filters around which ionophore or channel frameworks can be constructed [22,23].…”

Conformational and orientation studies of artificial ion channels incorporated into lipid bilayers

“…[5][6][7][8][9][10][11][12] Some successful approach gave compounds that showed single-channel activity. [13][14][15][16][17][18][19][20][21][22][23][24][25] In our laboratory, we have described a general strategy to prepare supramolecular devices having a predictable structure 26 using polypeptides as frameworks. Using this strategy, we have reported the preparation of the 21 amino acid peptide, 1, bearing six 21-crown-7 moieties (6) that displayed typical single-channel activity, [27][28][29] and ion transport ability similar to gramicidin A in vesicle experiments.…”

Self-assembling subnanometer pores with unusual mass-transport properties

“…Biological nanotubular complexes, such as the non-selective pore formed by α-hemolysin 2 , and the highly selective channels of ions 3 and water 4 , provide some of the most spectacular examples of supramolecular assemblies with extraordinary structural and functional sophistication. Taking lessons from biological assemblies, the recent integration of molecular design and synthesis with noncovalent forces such as hydrogenbonding, electrostatic, hydrophobic, π − π and ion-π interactions, along with metal-organic architectures and covalent capture of supramolecular assemblies, has made a significant inroad towards producing various synthetic channels and pores, either from organic building blocks or from cyclic peptides [5][6][7][8][9][10][11][12][13] . Many of these synthetic molecular and supramolecular structures exhibit interesting masstransporting properties.…”