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Ion Permeation by a Folded Multiblock Amphiphilic Oligomer Achieved by Hierarchical Construction of Self-Assembled Nanopores
journal contribution
posted on 2012-12-05, 00:00 authored by Takahiro Muraoka, Tatsuya Shima, Tsutomu Hamada, Masamune Morita, Masahiro Takagi, Kazuhito
V. Tabata, Hiroyuki Noji, Kazushi KinbaraA 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.