Ionic conductance of synthetic channels: analysis, lessons, and recommendations

Chui, Jonathan K. W.; Fyles, Thomas M.

doi:10.1039/c1cs15099e

Cited by 164 publications

(187 citation statements)

References 134 publications

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“…We classified these signals by reference to Fyles group's study. 18 The three types of signals, i.e., step-like, multi-level, and spike signals, obtained reflect the several pore-forming modes of magainin 1. Previous studies have proposed 19 that magainin and many other AMPs form peptide helices and associate to form a bundle with a central lumen, similar to a barrel made of helical peptides, which is the "barrel-stave model."…”

Section: Resultsmentioning

confidence: 89%

Channel Current Analysis for Pore-forming Properties of an Antimicrobial Peptide, Magainin 1, Using the Droplet Contact Method

Watanabe

Kawano

2016

ANAL. SCI.

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This study describes the pore-forming properties of magainin 1 in planar lipid bilayers. These bilayers were prepared by the droplet contact method, which was executed on a microfabricated device for a high-throughput study. We arrayed four droplet chambers parallelly in the single device, and the current measurements were carried out simultaneously. Using this system, we measured the channel current conductance of magainin 1. We determined the pore size and the number of assembling monomers in magainin pores in mammalian and bacterial model membranes. This system is a powerful tool for analyzing transmembrane peptides and their antimicrobial activities.

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Section: Resultsmentioning

confidence: 89%

Channel Current Analysis for Pore-forming Properties of an Antimicrobial Peptide, Magainin 1, Using the Droplet Contact Method

Watanabe

Kawano

2016

ANAL. SCI.

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“…36 We found that this ester-attached PA [5] derivative adopted a tubular conformation and stacked cofacially to form infinite uniform organic tubes in the solid state. In particular, the tubes contained water molecules that were arranged into single wires associated by continuous hydrogen bonds ( Figure 2).…”

Section: Proton Channelmentioning

confidence: 98%

Tubular Unimolecular Transmembrane Channels: Construction Strategy and Transport Activities

et al. 2015

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Lipid bilayer membranes separate living cells from their environment. Membrane proteins are responsible for the processing of ion and molecular inputs and exports, sensing stimuli and signals across the bilayers, which may operate in a channel or carrier mechanism. Inspired by these wide-ranging functions of membrane proteins, chemists have made great efforts in constructing synthetic mimics in order to understand the transport mechanisms, create materials for separation, and develop therapeutic agents. Since the report of an alkylated cyclodextrin for transporting Cu(2+) and Co(2+) by Tabushi and co-workers in 1982, chemists have constructed a variety of artificial transmembrane channels by making use of either the multimolecular self-assembly or unimolecular strategy. In the context of the design of unimolecular channels, important advances have been made, including, among others, the tethering of natural gramicidin A or alamethicin and the modification of various macrocycles such as crown ethers, cyclodextrins, calixarenes, and cucurbiturils. Many of these unimolecular channels exhibit high transport ability for metal ions, particularly K(+) and Na(+). Concerning the development of artificial channels based on macrocyclic frameworks, one straightforward and efficient approach is to introduce discrete chains to reinforce their capability to insert into bilayers. Currently, this approach has found the widest applications in the systems of crown ethers and calixarenes. We envisioned that for macrocycle-based unimolecular channels, control of the arrangement of the appended chains in the upward and/or downward direction would favor the insertion of the molecular systems into bilayers, while the introduction of additional interactions among the chains would further stabilize a tubular conformation. Both factors should be helpful for the formation of new efficient channels. In this Account, we discuss our efforts in designing new unimolecular artificial channels from tubular pillar[n]arenes by extending their lengths with various ester, hydrazide, and short peptide chains. We have utilized well-defined pillar[5]arene and pillar[6]arene as rigid frameworks that allow the appended chains to afford extended tubular structures. We demonstrate that the hydrazide and peptide chains form intramolecular N-H···O═C hydrogen bonds that enhance the tubular conformation of the whole molecule. The new pillar[n]arene derivatives have been successfully applied as unimolecular channels for the selective transport of protons, water, and amino acids and the voltage-gated transport of K(+). We also show that aromatic hydrazide helices and macrocycles appended with peptide chains are able to mediate the selective transport of NH4(+).

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“…[1][2][3] The limitations associated with the stability and characterization of large proteins, inspires researchers to develop oligopeptides capable of ion-selective membrane transport. [4][5][6] Non-toxic low molecular weight peptidic ion transporters are potentially useful for pharmaceutical applications as well as attractive model systems for gaining mechanistic insights into membrane transport through larger proteins. A variety of the small oligopeptide ion transporters are derived from cyclic peptides comprising alternating D-and L-amino acids.…”

Section: Introductionmentioning

confidence: 99%