title: Ion permeation by a folded multiblock amphiphilic oligomer achieved by hierarchical construction of self-assembled nanopores.
abstract: A multiblock amphiphilic molecule 1, with a tetrameric alternating sequence of hydrophilic and hydrophobic units, adopts a folded structure in a liposomal membrane like a multipass transmembrane protein, and is able to transport alkali metal cations through the membrane. Hill's analysis and conductance measurements, analyzed by the Hille equation, revealed that the tetrameric assembly of 1 forms a 0.53 nm channel allowing for permeation of cations. Since neither 3, bearing flexible hydrophobic units and forming no stacked structures in the membrane, nor 2, a monomeric version of 1, is able to transport cations, the folded conformation of 1 in the membrane is likely essential for realizing its function. Thus, function and hierarchically formed higher-order structures of 1, is strongly correlated with each other like proteins and other biological macromolecules.
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan. kinbara@tagen.tohoku.ac.jp
authors.forename: Takahiro
authors.initials: T
authors.lastname: Muraoka
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Shima
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hamada
authors.forename: Masamune
authors.initials: M
authors.lastname: Morita
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takagi
authors.forename: Kazuhito V
authors.initials: KV
authors.lastname: Tabata
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Noji
authors.forename: Kazushi
authors.initials: K
authors.lastname: Kinbara
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D007477:Ions; D008051:Lipid Bilayers / Q000737:chemistry*; D015394:Molecular Structure; D058608:Nanopores; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D017510:Protein Folding; D013050:Spectrometry, Fluorescence; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D007477:Ions; D008051:Lipid Bilayers; D009838:Oligodeoxyribonucleotides; D053835:Unilamellar Liposomes