The central ‘relay’ unit in hydraphile channels as a model for the water-and-ion ‘capsule’ of channel proteins

Murray, Colin; Shabany, Hossein; Gokel, George W.

doi:10.1039/b005431n

Cited by 39 publications

(43 citation statements)

References 17 publications

(13 reference statements)

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“…It thus seemed likely that the central relay macrocycle was parallel to the fatty acid chain axis rather than parallel to the membrane surfaces. Additional studies confirmed this assumption and suggested that the central relay interacts with the solvated cation rather than the cation itself [58].…”

Section: Defining the Conformation In The Bilayermentioning

confidence: 84%

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Coordination and transport of alkali metal cations through phospholipid bilayer membranes by hydraphile channels

Gokel

Daschbach

2008

Coordination Chemistry Reviews

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Hydraphiles are synthetic ionophores that were designed to mimic some properties of protein channels that conduct such cations as sodium. They use macrocyclic (crown) polyethers as amphiphilic headgroups and as entry and exit portals. Their overall length is controlled by covalent links between the two headgroups (distal macrocycles) and the "central relay" unit, typically also an azacrown. The hydraphiles insert in the bilayer membranes of synthetic phospholipid vesicles or vital cells and mediate the transport of cations. The hydraphiles were intended to be models but they are functional channels. Because they are symmetric, they are non-rectifying but they show open-close behavior characteristic of natural channels. Because they are non-rectifying, when they insert into a microbial membrane, they lead to a rapid change in osmotic balance that proves fatal to bacteria.

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Section: Defining the Conformation In The Bilayermentioning

confidence: 84%

“…The successful function of channels having central relay units [58] too small (e.g. 3) to pass Na + , strongly suggested that in 1, the third macrocycle was positioned perpendicular to the other two and parallel to the axes of the fatty acid chains.…”

Section: 31mentioning

confidence: 99%

Coordination and transport of alkali metal cations through phospholipid bilayer membranes by hydraphile channels

Gokel

Daschbach

2008

Coordination Chemistry Reviews

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“…4,13-Diaza-18-crown-6 was then treated with an excess of the dibromopropoxynaphthalene in the presence of Na 2 CO 3 and catalytic KI. Br(CH 2 ) 3 OC 10 H 6 O (CH 2 ) 3 〈N18N〉(CH 2 ) 3 OC 10 H 6 O(CH 2 ) 3 Br was obtained in 40% yield. This dibromide was treated with 2 equiv of N-dodecyl-4,13-diaza-18-crown-6 to give 5 (13%) as a nearly colorless solid, mp 103-104.5 °C.…”

Section: Compounds Used In This Studymentioning

confidence: 97%

“…20 The phospholipid were obtained as CHCl 3 solutions, which were dried to lipid films and stored under vacuum at ambient temperature. The vesicles were prepared by dissolving a dry lipid film in 0.3 mL diethyl ether and 0.3 mL buffer (750 mM NaCl/15 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES), pH 7.0).…”

Section: Vesicle Preparationmentioning

confidence: 99%

The influence of aromatic residues in hydraphile spacer units: assay by ion selective electrode methods and in bacteria

Meyer

Leevy

Pajewski

et al. 2005

Bioorganic & Medicinal Chemistry

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A small library of hydraphiles has been prepared that incorporates either 1,4-phenylenedioxy or 2,6-naphthalenedioxy within the spacer chains. The side chains attached to the distal macrocycles in these tris(macrocyclic) compounds are either n-dodecyl or benzyl. The presence of the arenes subunits significantly affect sodium cation release from vesicles. The efficacy of ion transport is paralleled by the toxicity of these compounds to Bacillus subtilis.

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“…Extensive studies have characterized the headgroup position [24] and function [25], the orientation [26] of the central macrocycle, and the channel's aggregation state within the phospholipid bilayer [27]. As noted above, linking the sidechains improved ionophoretic activity.…”

Section: Introductionmentioning

confidence: 95%

The effect of twin‐tailed sidearms on sodium cation transport in synthetic hydraphile cation channels

Shabany

Pajewski

Abel

et al. 2001

Journal of Heterocyclic Chem

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The preparation of novel tris(macrocycle)s that transport Na + through phospholipid bilayers is reported. All of the reported structures have the following structural elements: sidechain-macrocycle-spacer-macrocycle-spacer-macrocycle-sidechain. The overall extension of the channel system is defined by the lengths of the spacer chains. The flexible sidearms are thought to be aligned with the lipid axis and opposite to the spacer chains. To the extent the spacer chains contribute to organization of the structure and isolation of the cation-containing pore from the surrounding lipid chains, more hydrophobic chains are expected to enhance cation transport. A comparison of C 12 H 25 (CH 2 ) 12 (CH 2 ) 12 C 12 H 25 , 1, with (C 12 H 25 ) 2 N(CH 2 ) 2 (CH 2 ) 12 (CH 2 ) 12 (CH 2 ) 2 N(C 12 H 25 ) 2 , 11, shows that the Na + transport is, indeed, enhanced.

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The central ‘relay’ unit in hydraphile channels as a model for the water-and-ion ‘capsule’ of channel proteins

Abstract: The central relay of hydraphile channels is a model for the central ion-capsule of the KcsA K1 K + -conducting channel of Streptomyces lividans; organization of water and concomitant electrostatic stabilization of a transient K + appear to be the functions in both cases.

Cited by 39 publications

References 17 publications

Coordination and transport of alkali metal cations through phospholipid bilayer membranes by hydraphile channels

Coordination and transport of alkali metal cations through phospholipid bilayer membranes by hydraphile channels

The influence of aromatic residues in hydraphile spacer units: assay by ion selective electrode methods and in bacteria

The effect of twin‐tailed sidearms on sodium cation transport in synthetic hydraphile cation channels

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