Alkalikationen‐Spezifität und Träger‐Eigenschaften der Antibiotica Nigericin und Monensin

Lutz, Werner; Wipf, H.‐K.; Simon, W.

doi:10.1002/hlca.19700530723

Cited by 69 publications

(25 citation statements)

References 21 publications

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“…Einen Hohepunkt erreichte die Komplexchemie der protonischen ,,Chelanden"[371 rnit den ,,Komplexonen" [Ethylendiamintetraessigsaure (EDTA) (27) verschiedener Kettenlange fur Na@, KO, Cs@, T1@[611 (potentiometrisch und konduktometrisch, in CH30H) zeigten, daB eine Vermehrung der Anzahl der Koordinationsstellen (Ether-0-Atome) die Stabilitatskonstanten und die Selektivitat K@/Na@ erhoht; Ersatz der beiden Methoxy-Kettenenden durch primare Saureamidgruppen oder Estergruppen verschlechtert die Komplexierungseigenschaften der Liganden.…”

Section: Chelate: Alkalimetallkomplexe (Potentiell) Saurer Offenkettiunclassified

“…Den niedrigen Stabilitatskonstanten entsprechend -auch in wenig polaren organischen Losungsmitteln -waren kristatline Atk~limefatlkomplexe von solchen ,,einfachen" nichtcyclischen Oligoethylenglycolethern (27), den Glymen, bis vor kurzem nicht bekanntt6'I; dies gilt auch fur Liganden, die eine durch ortho-substituierte Arylgruppen abgewinkelte und teilweise versteifte Polyetherkette (Entropiegewinn) rnit bis zu zehn Sauerstoffatomen enthalten["l.…”

Section: Chelate: Alkalimetallkomplexe (Potentiell) Saurer Offenkettiunclassified

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Vielzähnige nichtcyclische Neutralliganden und ihre Komplexierung

1979

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Section: Chelate: Alkalimetallkomplexe (Potentiell) Saurer Offenkettiunclassified

Vielzähnige nichtcyclische Neutralliganden und ihre Komplexierung

1979

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“…The shielded cation can be solubilized in media of low polarity, or carried across the hydrocarbon interior of a membrane as a mobile complex. Formation of several cation-ionophore complexes in organic solvents has been demonstrated by various physicochemical methods (8,9,11,12), but stability of the complexes is drastically reduced by addition of water to the solvent (8,9) so that complex formation in purely aqueous media cannot be detected (8). Pressman (13) developed a method to quantitate complex formation by utilizing a two-phase system of water and butanol-toluene.…”

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The Detection of Ionophorous Antibiotic-Cation Complexes in Water with Fluorescent Probes

Feinstein

Felsenfeld

1971

Proc. Natl. Acad. Sci. U.S.A.

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The binding of alkali cations by the ionophorous antibiotics valinomycin, nigericin, alamethicin, and the macrotetralide actins has been shown to occur, in aqueous media, by the use of the fluorescent probes I-anilino-8-naphthalene sulfonate and 2-p-toluidinyl-6-naphthalene sulfonate. The interaction of the ionophore-cation complexes with the fluorescent dyes produced enhanced fluorescence emission, increased lifetime and polarization, and a significant blue-shift of the emission maxima of the fluorescence spectrum. At constant antibiotic and fluorophore concentrations in water, the intensity of the fluorescence emission was found to be a function of the cation concentration. This permitted relative cation affinities to be determined for alamethicin (Na+ K+), valinomycin (Rb+ > K+ > Cs+), nigericin (K > Rb+ > Na4 > Cs+) and trinactin (NH4+ > K+ > Rb+ > Cs+).Certain microbial metabolites, termed ionophorous antibiotics, have been observed to produce profound effects upon passive ion transport in erythrocytes, bacteria, lipid bilayer membranes, and energy-dependent ion transport in mitochondria (1-3). These phenomena are all markedly dependent upon the alkali-cation composition of the medium. This dependency has been accounted for by the discovery of the remarkably specific alkali-cation binding properties of these antibiotics (1,4,5). Among the ionophores are such groups as: (a) the cyclodepsipeptides (i.e., valinomycin and the enniatin antibiotics) and the nactin cyclodepsides, which form positively charged complexes with alkali-cations, (b) nigericin and monensin, linear chains of oxygen-containing heterocyclic rings that cyclize by hydrogen bonding between carbonyl and hydroxyl groups at opposite ends of the molecule, and whose cation complexes are electrically neutral, and (c) alamethicin, a cyclic polypeptide with a free carboxyl group that can form neutral or net positively charged complexes. Cation selectivity in organic solvents or model membrane systems varies from high K+/Na+ affinity for valinomycin, macrolide actins, and nigericin, and poor discrimination between these two cations for alamethicin, to Na+ preference for monensin (1,(4)(5)(6)26). A common property of all these ionophores is the ability to carry alkali-cations across lipid barriers, or into solvents of low polarity (1, 4, 5). X-ray crystallography, proton magnetic resonance, infrared spectroscopy, and optical rotatory dispersion have revealed that the cations are associated through induced dipole interactions with carbonyl, ether, or hydroxyl oxygen atoms of the ionophore. Conformational changes occur upon reaction with the cation, with the result that the cation (stripped of its hydration shell) resides within a cavity formed by the polar oxygen groups. The latter are in turn enclosed within the lipophilic portions of the ionophore, which comprise the exterior of the complex (7-10). The shielded cation can be solubilized in media of low polarity, or carried across the hydrocarbon interior of a membrane as a mobile complex. Forma...

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“…[29] Все атомы водорода выявлены в разностном синтезе и уточня-лись в изотропном приближении. ras-(С (19) c=13.814(3) Å, α=75.67(2)°, β=74.637(17)°, γ=70.12(2) (I>2σ(I)). Рентгеноструктурные экспериментальные данные для структур депонированы в Кембриджском банке структурных данных под номерами …”

Section: рентгеноструктурное исследованиеunclassified

“…В наших исследованиях введение полиэфирного фрагмента позволило повысить активность и существен-но снизить токсичность известных туберкулостати-ков. [17,18] Следует ожидать, что наличие соответствующе-го фрагмента в 6,7-дигидроазоло[1,5-a]пиримидиновых краунофанах (Схема 1), способных имитировать пове-дение природных ионофоров [19,20] (группы антибиотиков нонактина и нигерицина), может существенно повлиять на вышеуказанную активность.…”

Section: Introductionunclassified