Redox properties of K-group vitamins

Ksenzhek, O.S.; Petrova, S. A.; Kolodyazhny, M.V.; Oleinik, S. V.

doi:10.1016/0302-4598(77)80035-4

Cited by 24 publications

(21 citation statements)

References 5 publications

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“…Phenazine methosulphate therefore functions in a different way than menadione, which was shown to replace the natural menaquinone [lo]. Such a difference in the interaction site of menadione and phenazine methosulphate with the respiratory chain also agrees with the different standard potentials at pH 7 of both electron mediators (Ed of menadione = -16 mV; Ed of phenazine methosulphate = 80 mV [20,21]). …”

Section: Discussionsupporting

confidence: 65%

Site of Interaction between Phenazine Methosulphate and the Respiratory Chain of Bacillus subtilis

Bisschop

Bergsma²,

Konings³

1979

European Journal of Biochemistry

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Membrane vesicles from Bacillus subtilis W23 and from the menaquinone-deficient Bacillus subfilis aroD were incubated with phenazine methosulphate and excess soluble phenazine methosulphate was subsequently removed by washing (preincubated vesicles). Phenazine methosulphate which remains attached to the membrane is accessible from the outer surface of the membrane because it can be reduced chemically by NADH or ascorbate and the reduced forms can mediate electrons to horse heart cytochrome c in the external medium of the membrane vesicles.The oxidation rates of ascorbate in preincubated vesicles of B. subtilis W23 and B. subtilis aroD and of NADH in preincubated vesicles of B. subtilis aroD increased with increasing amounts of phenazine methosulphate attached per mg membrane protein. Electrons from membrane-attached reduced phenazine methosulphate are essentially all mediated to the terminal part of the respiratory chain before cytochrome a601 because the oxidation of reduced phenazine methosulphate is almost completely inhibited by cyanide and only to a small extent by 2-heptyl-4-hydroxy-quinoline-N-oxide while NADH oxidase is strongly inhibited by both compounds. Furthermore, reduced phenazine methosulphate reduces completely cytochrome a601 and not all cytochromes b560 and ~5 5 3 .Active transport of amino acids is at least ten-fold more effectively stimulated by NADH or ascorbate oxidation via phenazine methosulphate than by NADH oxidation via NADH dehydrogenase. Possible explanations are discussed.Active transport of amino acids and other solutes by membrane vesicles of Bacillus subtilis and many other bacteria can be energized by electron transfer in electron transport, systems [1,2]. Under aerobic conditions the highest rates of transport are often obtained with the non-physiological electron donor system ascorbate/phenazine methosulphate [l -51. Oxidation of ascorbate/phenazine methosulphate via the respiratory chain leads to the generation of a proton-motive force [6,7] which is the direct driving force for active transport of solutes across the membrane and other energy-requiring membrane functions [S].Although ascorbate/phenazine methosulphate proved to be a very useful tool in studies on energy transduction across cytoplasmic membranes the site at which phenazine methosulphate transfers electrons to the respiratory chain is yet unknown for most organisms. In order to understand the process of energy transduction during ascorbate/phenazine methosulphate oxidation we decided to investigate this aspect in B. subtilis.Another reason which led to this investigation is the following. Membrane vesicles of B. subtilis oxidize reduced nicotinamide adenine dinucleotide (NADH) at a high rate and a high rate of solute transport is obtained with this electron donor [5,9]. Membrane vesicles of a menaquinone-deficient mutant (B. subtilis aroD) oxidize NADH at a low rate and NADH does not support transport [lo]. NADH-oxidation and NADH-driven transport could be restored in these membrane vesicles with the menaquinon...

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Section: Discussionsupporting

confidence: 65%

Site of Interaction between Phenazine Methosulphate and the Respiratory Chain of Bacillus subtilis

Bisschop

Bergsma²,

Konings³

1979

European Journal of Biochemistry

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“…The electron number corresponding to reduction peak 6 was estimated with respect to the monoelectronic reduction wave of menadione (n ¼ 1.9) (Figure 2) and by controlled potential electrolysis (n ¼ 2.2). This result and the absence of the reversible peak 3-4, shown in Figure 4a, let us propose that the selfprotonation reactions (9,11) have been essentially suppressed. This is because phthiocol (pKa DMSO Х pKa phenol DMSO ¼ 18.03) is a weaker acid than benzoic acid (pKa DMSO ¼ 11) [20].…”

Section: The Electrochemical Reduction Of Phthiocol In the Presence Omentioning

confidence: 77%

“…It has been proposed that the antihemorrhagic activity of these compounds can be related to their reduction potential [1,9], which depend on the electron-releasing or electron-withdrawing power of the substituents [10]. Thus, it has been observed that the less active phthiocol, possessing an electronwithdrawing substituent, is more easily reduced than the corresponding menadione [9].…”

Section: Introductionmentioning

confidence: 98%

Cyclic Voltammetry of Two Analogue K-Group Vitamin Compounds in Dimethylsulfoxide

González

1998

Electroanalysis

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The electrochemical reduction of two analogue K-group vitamin compounds, menadione and phthiocol, was studied by cyclic voltammetry in DMSO on glassy carbon electrodes. The reduction process of the more biologically active of these compounds (menadione), is associated with the formation of the semiquinone anion radical and the dianion. Two separated reversible one-electron peaks were observed. In contrast, the less biologically active phthiocol exhibits a single irreversible 2/3-electron peak which is explained by an ECE-DISP1 self-protonation mechanism. In the presence of a donor proton such as benzoic acid, menadione and phthiocol are reduced both through a sequence of consecutive electron transfer and protonation reactions occurring via an irreversible two-electron ECE-DISP1 mechanism.

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“…b) Pourbaix diagram for the electrochemical reduction of vitamin K 1 as reported by Petrova et al [9] VK1 refers to the quinone form of vitamin K 1 , VK1H 2 represents the reduced quinol form, VK1H indicates the semiquinone, VK1 ¥ OH À is the oxidised form of vitamin K 1 after reaction with hydroxide ions, and VK1H À refers to a deprotonated form of VK1H 2 . c) Illustration of the electrochemical processes suggested by Petrova et al [9] the long phytyl side chain, being reminiscent of effects previously observed in our group for a different set of homologous compounds. [24] It is the aim of this work to investigate redox processes in vitamin K 1 microdroplets in the light of Figure 1 b.…”

Section: Introductionmentioning

confidence: 98%

“…Petrova and co-workers [9] studied the electrochemical reduction of vitamin K 1 in a thin-layer cell. Their results are summarised in Figure 1 b and c. The authors observed that the redox potential of vitamin K 1 is shifted to more negative potentials compared with that for vitamin K 3 , which is a consequence of Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Studies of Vitamin K₁Microdroplets: Electrocatalytic Hydrogen Evolution

2003

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The voltammetry of a basal-plane pyrolytic graphite electrode modified with a random ensemble of unsupported microdroplets of vitamin K, is investigated when the electrode is immersed in aqueous electrolytes. It is shown that in dilute acidic solutions, electroreduction occurs in a single two-electron two-proton process to yield the corresponding hydroquinone at the electrode\vitamin K1 microdroplet\aqueous-electrolyte three-phase boundary. On addition of ionic alkali-metal salts to the aqueous acidic phase, the electrochemical reduction of vitamin K1 to the quinol is accompanied by catalytic hydrogen evolution within and alkali-metal-cation insertion into the organic microdroplets. In strongly alkaline solutions, electrochemical reduction of vitamin K1 at the triple-phase junction is proposed as being a single two-electron process with concomitant uptake of alkali-metal cations in order to maintain electroneutrality within the oil phase. Surprisingly, the relative ease of cation insertion into the oil phase is demonstrated to be governed by the degree of ion-pair formation rather than by the Gibbs transfer energy of the cation across the liquid\liquid interface.

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Redox properties of K-group vitamins

Cited by 24 publications

References 5 publications

Site of Interaction between Phenazine Methosulphate and the Respiratory Chain of Bacillus subtilis

Site of Interaction between Phenazine Methosulphate and the Respiratory Chain of Bacillus subtilis

Cyclic Voltammetry of Two Analogue K-Group Vitamin Compounds in Dimethylsulfoxide

Electrochemical Studies of Vitamin K₁Microdroplets: Electrocatalytic Hydrogen Evolution

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Redox properties of K-group vitamins

Cited by 24 publications

References 5 publications

Site of Interaction between Phenazine Methosulphate and the Respiratory Chain of Bacillus subtilis

Site of Interaction between Phenazine Methosulphate and the Respiratory Chain of Bacillus subtilis

Cyclic Voltammetry of Two Analogue K-Group Vitamin Compounds in Dimethylsulfoxide

Electrochemical Studies of Vitamin K1Microdroplets: Electrocatalytic Hydrogen Evolution

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Electrochemical Studies of Vitamin K₁Microdroplets: Electrocatalytic Hydrogen Evolution