Cation permeability induced by valinomycin, gramicidin D and amphotericin B in large lipidic unilamellar vesicles studied by 31P-NMR

Hervé, Martine; Cybulska, Barbara; Gary-Bobo, C.M.

doi:10.1007/bf00254070

Cited by 48 publications

(34 citation statements)

References 12 publications

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“…[33] We previously reported that nonfluorinated AmB-ergosterol conjugate 3 exhibits a higher activity than its cholesterol counterpart 5 in liposome assays. [18] In the present experiments, fluorine-labelled conjugate 2 showed a somewhat lower efficacy than nonfluorinated conjugate 3; at 3.6 mm, amphotericin B, conjugate 2 and conjugate 4 induced 32 %, 50 % and 49 % permeabilisation of liposomes, respectively, whereas 3 induced 80 % permeabilisation at the same concentration (see the Supporting Information for details).…”

Section: Resultsmentioning

confidence: 99%

“…Further purification of conjugate 2 was performed by a column chromatography with JAIGEL-GS310 (f21.5 300 mm, Japan Analytical Industry Co., Ltd.) and a CHCl 3 /MeOH (3:1) solvent system with a LC-918 recycling preparative HPLC system. Finally, AmB-C 2 -(6-F)Erg Liposome preparations: Large unilamellar vesicles (LUV) were prepared according to the methods reported by HervØ et al [33] Briefly, egg phosphatidylcholine (12 mmol) and either AmB-C 2 -Sterol or AmB (3.6 nmol) were dissolved in chloroform/methanol (3:1) and the mixture was evaporated to a thin film in a 10-mL test tube. After the film was dried under vacuum for over 8 h, 0.4 mm KH 2 PO 4 and 1 mm EDTA at pH 5.5 in H 2 O/ D 2 O (6:4; 166.7 mL) was added to the test tube.…”

Section: Methodsmentioning

confidence: 99%

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Self‐Assembled Amphotericin B Is Probably Surrounded by Ergosterol: Bimolecular Interactions as Evidenced by Solid‐State NMR and CD Spectra

Kasai

Matsumori

Umegawa

et al. 2008

Chemistry A European J

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Amphotericin B (AmB) is thought to exert its pharmacological effects by forming a barrel-stave assembly with ergosterol in fungal membranes. To examine the interaction between AmB and ergosterol (Erg) or cholesterol (Cho), (13)C- and (19)F-labelled covalent conjugates were prepared as reported previously (N. Matsumori et al. Chem. Biol. 2004, 11, 673-679). The CD spectra of the conjugates in a membrane-bound form suggested that the distance between the heptaene moieties of the ergosterol conjugates AmB-C(2)-(6-F)Erg 2 and AmB-C(2)-Erg 3 is similar to that of AmB in ergosterol-containing membranes, but significantly larger than that of AmB in nonsterol or cholesterol-containing membranes. These observations suggest that, as is the case with ergosterol-containing membranes, the conjugated sterol moiety prevents the close contact between the heptaene moieties within the membrane that would reduce channel conductivity of the AmB assemblies. To further investigate this bimolecular interaction, we recorded the solid-state NMR spectra of conjugates 2 and AmB-C(2)-(6-F)Cho 4, which are composed of uniformly (13)C-labelled AmB and 6-fluorinated ergosterol or cholesterol; the conjugates were expected to facilitate the estimation of distances between the fluorine and carbon atoms. By using rotor-synchronous double resonance (rotational echo double resonance of X cluster; RDX) experiments, we deduced the distance between the fluorine atom and its nearest carbon atom in the heptaene moiety of 2 to be less than 8.6 A. This indicates that the B ring of ergosterol comes close to the AmB polyene moiety. A conformational search of the AmB-ergosterol conjugate by using distance constraints derived from the RDX results suggested that ergosterol molecules possibly surround the AmB assembly, which is in contrast with the conventional image in which ergosterol is inserted into AmB molecules.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Self‐Assembled Amphotericin B Is Probably Surrounded by Ergosterol: Bimolecular Interactions as Evidenced by Solid‐State NMR and CD Spectra

Kasai

Matsumori

Umegawa

et al. 2008

Chemistry A European J

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“…Proton flux through a phospholipid bilayer was demonstrated by Menger and coworkers using the oligoethylene glycol ester, CH 3 (CH 2 ) 10 COO(CH 2 CH 2 O) 5 CH 2 Ph, as a synthetic transporter [38]. Fyles and coworkers adapted the method of Gary-Bobo and coworkers [39], by competing proton and cation flux, to quantitate alkali metal cation transport rates and selectivity [40].…”

Section: Fluorescent Methods Of Analysis-mentioning

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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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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“…In the late 1970s, we considered how one might mimic the effectiveness of the mitochondrial potassium transporter valinomycin. [75] The solid-state structure of valinomycin showed that the apparently too-large macrocycle (36-membered) folds into a ''tennis-ball seam'' [76] arrangement around K ϩ . [77] This envelops the cation but the open structure of the unbound host affords good binding dynamics.…”

Section: Lariat Ethersmentioning

confidence: 99%

Experimental Evidence for Alkali Metal Cation−π Interactions

2000

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Cation permeability induced by valinomycin, gramicidin D and amphotericin B in large lipidic unilamellar vesicles studied by 31P-NMR

Cited by 48 publications

References 12 publications

Self‐Assembled Amphotericin B Is Probably Surrounded by Ergosterol: Bimolecular Interactions as Evidenced by Solid‐State NMR and CD Spectra

Self‐Assembled Amphotericin B Is Probably Surrounded by Ergosterol: Bimolecular Interactions as Evidenced by Solid‐State NMR and CD Spectra

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

Experimental Evidence for Alkali Metal Cation−π Interactions

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