The physicochemical basis of the functioning of biological membranes: Dynamic conformational properties of enniatin B and its K+ complex in solution

Ovchinnikov, Yu.A.; Иванов, В. Т.; Evstratov, A. V.; Bystrov, V. F.; Абдуллаев, Н. Д.; Popov, E. M.; Lipkind, G. M.; Архипова, С. Ф.; Efremov, E. S.; Shemyakin, M. M.

doi:10.1016/0006-291x(69)90863-8

Cited by 72 publications

(3 citation statements)

References 7 publications

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“…The NOE correlations between N Me-Leu 6 (δ H 3.01) and H-Hmp 1 -2 (δ H 5.25), between N Me-Val 4 (δ H 3.02) and H-Hmp 5 -2 (δ H 5.38), and between N Me-Val 2 (δ H 3.04) and H-Hmp 3 -2 (δ H 5.14) suggested that these protons were on the same side. It is reported that enniatin B had a strong negative Cotton effect at 230 nm. , The ECD spectrum of 4 (236 nm, Δε – 1.73) (Figure S35) displayed a similar negative Cotton effect, indicating the stereochemistry was the same as enniatin B. In conclusion, the absolute configuration of 4 was determined to possess l -amino acid and d -hydroxyisovalerate.…”

Section: Resultsmentioning

confidence: 69%

Cytotoxic Cyclodepsipeptides and Cyclopentane Derivatives from a Plant-Associated Fungus Fusarium sp.

et al. 2022

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In this work, four new cyclodepsipeptides, fusarihexins C–E (1–3) and enniatin Q (4), four new cyclopentane derivatives, fusarilins A–D (5–8), together with eight known compounds (9–16), were isolated from cultures of the endophytic fungus Fusarium sp. The structures of the isolated compounds were elucidated by analysis of HRMS and NMR spectroscopic data. The absolute configurations were determined using Marfey’s method, a modified Mosher’s method, single-crystal X-ray diffraction analysis, and ECD analysis. The antitumor activities of the isolated compounds in vitro were evaluated. Cyclodepsipeptides displayed cytotoxicities against the Huh-7, MRMT-1, and HepG-2 cell lines. Compounds 4, 9, 10, and 12 with IC50 values of 1.0–9.1 μM exhibited the most potent cytotoxicities against the three cell lines as compared to the positive control-5-fluorouracil. Compounds 1–3 and 11 exhibited moderate cytotoxic activities (IC50 values of 10.7–20.1 μM).

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Section: Resultsmentioning

confidence: 69%

Cytotoxic Cyclodepsipeptides and Cyclopentane Derivatives from a Plant-Associated Fungus Fusarium sp.

et al. 2022

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“…NMR experiments [8,10] and circular dichroism (CD) experiments [7] give evidence for subtle differences between the K +, Rb + and Cs + complexes of valinomycin, and indicate a larger difference with the Na § complex. Ovchinnikov et al [15] have shown that the Li § Na § K + and Cs + complexes of enniatin B differ greatly with respect to the orientation of the complexing carbonyl groups about the complexed cation. These differences in complex conformation could easily express themselves in different solvent dependencies of the cation binding constants, and thus a solvent-dependent ion specificity.…”

Section: Flexibility Of Ionophore Complexesmentioning

confidence: 99%

Two-phase partition studies of alkali cation complexation by ionophores

Haynes

Pressman

1974

J. Membrain Biol.

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Summary. The partition of alkali cations and anions between an aqueous and an immiscible organic phase has been studied in the absence and presence of neutral and carboxylic ionophores of the valinomycin and nigericin types, respectively. Cation extraction into the organic phase was augmented considerably by the ionophores, and a cation specificity of K + >Rb+> Cs + N Na + was found for all the neutral ionophores tested. Evidence is given that the actual values of ion specificity are a function of the solvent polarity, especially for valinomycin where an inversion of the K+/Rb + specificity was observed. The ionophores examined have the following rank order of effectiveness for K + extraction into a standard organic phase consisting of 70% toluene-30% n-butanol: valinomycin > 18-crown-6 >> trinactin > enniatin B ~ dinactin > monaetin > nonactin. The ion affinity and selectivity data thus obtained have been compared with data previously reported.In a toluene-butanol solvent, extraction of cations in the absence of ionophores occurs as ion pairs. On the other hand, the neutral ionophores extract the cations by the mechanism of complexation, with the lipophilic anions coextracted as free gegenionic species at lower ionophore complex concentrations. When the concentration of extracted cations exceeds 1 x 10 -4 M, ion pairing between the ionophore complex and the anion occurs, and this tendency increases with increasing concentration and decreasing polarity of the organic phase. Anion pairing with the complexed cations is much less than for the free cations and this effect appears to be due to the larger distance of closest approach of the anion for the complexed cation.The mobile carrier concept of ionophore-mediated cation transport [2,17,18] implies that the efficiency of the cation-transport reaction will depend strongly upon the equilibrium constant of the complexation reaction within the membrane and the kinetics of the complexation [3,7,9,10,19] and transport reactions. In order to facilitate predictions about complexation affinities in biological membranes, the ability of various ionophores * Present address:

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“…When the K+ cation is replaced by the smaller Na' cation a characteristic change occurs in the enniatin conformation, similar to the closing of a flower [ 1,9] This is connected with decrease in the 0.. .M+ distance and a straightening out of the C=O...M' angle causing an increase in the positive charge electrical field component directed along the carbonyl bond. As a result the l3 C=O resonance for the Na' complex of beauvericin shifts by 1.7 and 2.3 ppm to lower field (table 2).…”

Section: Resultsmentioning

confidence: 99%

Biologically active alkali metal complexones. A¹³C‐NMR study of ion—dipole interaction

et al. 1972

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The physicochemical basis of the functioning of biological membranes: Dynamic conformational properties of enniatin B and its K+ complex in solution

Cited by 72 publications

References 7 publications

Cytotoxic Cyclodepsipeptides and Cyclopentane Derivatives from a Plant-Associated Fungus Fusarium sp.

Cytotoxic Cyclodepsipeptides and Cyclopentane Derivatives from a Plant-Associated Fungus Fusarium sp.

Two-phase partition studies of alkali cation complexation by ionophores

Biologically active alkali metal complexones. A¹³C‐NMR study of ion—dipole interaction

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The physicochemical basis of the functioning of biological membranes: Dynamic conformational properties of enniatin B and its K+ complex in solution

Cited by 72 publications

References 7 publications

Cytotoxic Cyclodepsipeptides and Cyclopentane Derivatives from a Plant-Associated Fungus Fusarium sp.

Cytotoxic Cyclodepsipeptides and Cyclopentane Derivatives from a Plant-Associated Fungus Fusarium sp.

Two-phase partition studies of alkali cation complexation by ionophores

Biologically active alkali metal complexones. A13C‐NMR study of ion—dipole interaction

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Biologically active alkali metal complexones. A¹³C‐NMR study of ion—dipole interaction