Voltammetric study on the electron transport through a bilayer lipid membrane containing neutral or ionic redox molecules

Shibata, Hiroyuki; Maeda, Kohji; Ichieda, Nobuyuki; Kasuno, Megumi; Yoshida, Yumi; Shirai, Osamu; Kihara, Sorin

doi:10.1016/s0022-0728(03)00312-7

Cited by 21 publications

(20 citation statements)

References 32 publications

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“…This method can be applied in aqueous solutions (28,39) as well as upon reconstituted planar bilayer lipid membranes (14)(15)(16)29). The use of cyclic voltammetry for determination of redox processes/conditions as described for hop compounds containing beer samples has considerable advantages compared to potentiometric measurements, as it is fast and reproducible (39).…”

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confidence: 99%

“…These redox couples are not necessarily the same in solutions and membranes. Nevertheless, for transmembrane electron transfer, proximity of the redox potentials of both is required (29). As lactic acid bacteria can contain millimolar concentrations of membrane-impermeable divalent manganese located near the cytoplasmic membrane (1) and hop compounds are amphiphilic compounds, a great deal of the above-described assumptions required for transmembrane redox processes is fulfilled.…”

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Mechanisms of Hop Inhibition Include the Transmembrane Redox Reaction

Behr

Vogel

2010

Appl Environ Microbiol

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In this work, a novel mechanistic model of hop inhibition beyond the proton ionophore action toward (beer spoiling) bacteria was developed. Investigations were performed with model systems using cyclic voltammetry for the determination of redox processes/conditions in connection with growth challenges with hop-sensitive and -resistant Lactobacillus brevis strains in the presence of oxidants. Cyclic voltammetry identified a transmembrane redox reaction of hop compounds at low pH (common in beer) and in the presence of manganese (present in millimolar levels in lactic acid bacteria). The antibacterial action of hop compounds could be extended from the described proton ionophore activity, lowering the intracellular pH, to pronounced redox reactivity, causing cellular oxidative damage. Accordingly, a correlation between the resistance of L. brevis strains to a sole oxidant to their resistance to hop could not be expected and was not detected. However, in connection with our recent study concerning hop ionophore properties and the resistance of hop-sensitive and -tolerant L. brevis strains toward proton ionophores (J. Behr and R. F. Vogel, J. Agric. Food Chem. 57:6074-6081, 2009), we suggest that both ionophore and oxidant resistance are required for survival under hop stress conditions and confirmed this correlation according to the novel mechanistic model. In consequence, the expression of several published hop resistance mechanisms involved in manganese binding/transport and intracellular redox balance, as well as that of proteins involved in oxidative stress under "highly reducing" conditions (cf. anaerobic cultivation and "antioxidative" hop compounds in the growth medium), is now comprehensible. Accordingly, hop resistance as a multifactorial dynamic property at least implies distinct resistance levels against two different mechanisms of hop inhibition, namely, proton ionophore-induced and oxidative stress-induced mechanisms. Beyond this specific model of hop inhibition, these investigations provide general insight on the role of electrophysiology and ion homeostasis in bacterial stress responses to membrane-active drugs.The inflorescences of the hop plant Humulus lupulus are traditionally used for beer brewing, due to the pleasant bitterness of hop compounds in beer and their additional inhibitory effect on bacteria. These antibiotic and bacteriostatic properties of hops comprise several inhibitory mechanisms. The described effects of hop compounds on bacteria are permeability changes in the bacterial cell wall (30), leakage of the cytoplasmic membrane and a subsequent inhibition of respiration, and protein, DNA, and RNA synthesis (42), as well as changes in leucine uptake and proton ionophore activity (33). In a recent study (5), we characterized the latter ionophore properties of hop compounds in a cell-free model system via bilayer lipid membrane (BLM) techniques in connection with growth challenges of hop-sensitive and -resistant Lactobacillus brevis strains. The antibacterial action of iso-␣-acids as prot...

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Mechanisms of Hop Inhibition Include the Transmembrane Redox Reaction

Behr

Vogel

2010

Appl Environ Microbiol

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“…49 2) Electron transfer at the W/O interface 50 39 In connection with the above-described subjects, there are reviews on charge transfers at the W/O interface written in Japanese. 69,70 Since the compositions of artificial systems are known and simple, the analyses of reactions observed with the artificial systems might be easy.…”

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confidence: 99%

“…The negative shift of E W1/LM results in the positive shift of the E LM/W2 (to B¤) because of the relation of Eq. (39). The adsorption at B¤ is stronger than that at the original E LM/W2 (B), since B¤ is E more remote from the point of zero charge, pzc, of the interface than B.…”

Section: Mechanism Of the Oscillation Of I W1-w2 Under An Appliedmentioning

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Biomimetic Charge Transfer Reactions at the Aqueous/Organic Solution Interface or through Artificial Membrane

et al. 2012

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Some biomimetic reactions observed with the aid of aqueous/organic, W/O, two phases or liquid membrane, LM, systems were introduced. The reactions introduced were mostly those reported by the group of present authors as follows; (1) (5) A new type of membrane transport reaction realized in the presence of an applied electrical potential gradient parallel to the W/ membrane interface. The processes of above-described reactions were elucidated based on the voltammetric methods and concepts taking into account the properties common to both artificial LMs and biomembranes. A method proposed by present authors for the elucidation of the membrane transport process was also introduced.

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Photochemical Systems of the Light Energy Conversion

Likhtenshtein

2012

Solar Energy Conversion

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Voltammetric study on the electron transport through a bilayer lipid membrane containing neutral or ionic redox molecules

Cited by 21 publications

References 32 publications

Mechanisms of Hop Inhibition Include the Transmembrane Redox Reaction

Mechanisms of Hop Inhibition Include the Transmembrane Redox Reaction

Biomimetic Charge Transfer Reactions at the Aqueous/Organic Solution Interface or through Artificial Membrane

Photochemical Systems of the Light Energy Conversion

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