Effect of pH on direct electron transfer between graphite and horseradish peroxidase

Ferapontova, Elena E.; Puganova, Elena A.

doi:10.1016/s0022-0728(01)00692-1

Cited by 47 publications

(58 citation statements)

References 26 publications

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“…The different pH optima for the two peroxidases resulted in maximum catalytic activity of RPTP towards ABTS at pH 3.5, and that of HRP at pH 4.8. Comparative studies of peroxidase activities upon addition of organic cosolvent were performed in buffer solutions, pH 6.0, as corresponding to the optimized bioelectrocatalytic activity of peroxidases in DETand in METwith catechol as mediator [33,40,41]. The enzymatic activity of both peroxidases decreased drastically upon addition of ethanol and acetonitrile to the aqueous buffer solution, in agreement with previously reported data [19,39].…”

Section: Enzymatic Activitysupporting

confidence: 85%

“…As in the case of HRP-modified graphite electrodes [33,40,41] the bioelectrocatalytic reduction of H 2 O 2 at RPTP-modified graphite started at potentials close to 700 mV and reached a maximum value at potentials below 300 mV. Assuming that in the potential range from 300 to À 50 mV the mechanism of the reaction remains the same, a detailed study of the kinetics of peroxidase bioelectrocatalysis at various pHs was performed at À 50 mV (vs. Ag j AgCl).…”

Section: Bioelectrocatalytic Function Of Peroxidases In Aqueous Mediamentioning

confidence: 99%

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Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

et al. 2005

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The bioelectrocatalytic function of two plant peroxidases, horseradish peroxidase (HRP) and a newly purified royal palm tree-leaf peroxidase (RPTP), was studied on graphite electrodes in aqueous buffer solutions, over the pH range 7.0 -3.0, and in aqueous buffer solutions, at pH 6.0, containing different amounts of a polar organic cosolvent, i.e., ethanol and acetonitrile. The kinetics of direct and of mediated (using catechol as mediator) reduction of H 2 O 2 at the HRP-and RPTP-modified graphite electrodes were analyzed amperometrically at À 50 mV(vs. Ag j AgCl j 0.1 M KCl) in a flow-through wall-jet electrochemical system. Values of the apparent rate constant of the heterogeneous electron transfer between the enzyme and graphite, k s , the rate constant for enzymatic reduction of H 2 O 2 , k 1 , and the rate constant of mediated reduction of H 2 O 2 , k 3, were determined using the modified Koutecky-Levich approach. Analysis of the variation of the rate constants and the response of the peroxidase-modified electrodes to H 2 O 2 with pH and content of the organic cosolvent demonstrated that maximal peroxidase bioelectrocatalytic activity occurred at pH 5.0 -6.0 and at concentrations of ethanol of 10 -20% v/v. At a lower pH, higher concentrations of ethanol, and in aqueous solutions of acetonitrile, the bioelectrocatalytic activity of the peroxidase-modified electrodes drastically decreased. However, contrary to the data for homogeneous catalysis, both peroxidases were bioelectrocatalytically active even in 95% organic co-solvents, thus demonstrating a stabilizing effect of the enzyme immobilization on the bioelectrocatalytic performance of the peroxidases. RPTP immobilized on graphite demonstrated lower overall activity but a higher pH-and organic cosolvent-stability than HRP.

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Section: Enzymatic Activitysupporting

confidence: 85%

Section: Bioelectrocatalytic Function Of Peroxidases In Aqueous Mediamentioning

confidence: 99%

Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

et al. 2005

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“…It is an expected result since the surface charges of the nHRP molecule and silver are the same and electrostatic interactions in this case hamper the adsorption of the enzyme at the electrode surface as was shown previously for gold [22]. The efficiency of direct ET is so low that when increasing the pH to 7.4, the concentration of protons at this pH provides additional kinetic restrictions for the proton-coupled ET reaction [12,18,19], with the result that no signal resulting from the bioelectrocatalytical reduction of H 2 O 2 could be traced. 2.…”

Section: Bioelectrocatalytical Reduction Of H 2 O 2 At Hrpmodified Sisupporting

confidence: 55%

“…The ability of engineered tags, such as the histidine tag, to chemisorb onto the surface of gold [25] or to produce covalent surface complexes with silver [26,27] through the histidine imidazol ring was used to improve the adsorption/orientation of the recombinant form at the electrode surface as well. The bioelectrocatalytical activity of the HRPs was analyzed at pH 6.0, providing an enhanced efficiency of the protoncoupled direct ET, compared to physiological pH 7.4 the more commonly pH used in previous investigations [12,18,19].…”

Section: Resultsmentioning

confidence: 99%

“…2, curves 1', 2'), catechol being chosen as mediator [17 ± 19]. It had been shown that for glycosylated nHRP adsorbed at graphite/carbon surfaces mediated ET is, as a rule, more efficient than direct ET [9,10,12]. This fact was attributed to that less than 50% of all active HRP molecules adsorbed at the electrode surface were in direct ET contact with the electrode.…”

Section: Bioelectrocatalytical Reduction Of H 2 O 2 At Hrpmodified Simentioning

confidence: 99%

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Bioelectrocatalytical Detection of H₂O₂ with Different Forms of Horseradish Peroxidase Directly Adsorbed at Polycrystalline Silver and Gold

Ferapontova

Gorton

2003

Electroanalysis

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The bioelectrocatalytical reduction of H 2 O 2 based on direct electron transfer (ET) between polycrystalline silver and the heme containing active site of horseradish peroxidase (HRP) is studied and compared with that obtained at gold. Native HRP and recombinant wild type HRP, containing additionally a six-histidine tag at the N-terminus, N His rHRP, have been used for adsorptive modification of the electrodes. The histidine sequences, introduced into the peroxidase structure by genetic engineering of recombinant HRP using an E. coli expression system, were supposed to affect adsorption/orientation of the enzyme at the electrode surface. The variations in direct ET efficiency when changing from gold to silver, as well as from native HRP to N His rHRP are analyzed and discussed, specifically, the high ET rates obtained with N His rHRP-modified preoxidized gold and silver electrodes, though accompanied by extremely rapid loss of the biolectrocatalytical activity of the latter (silver) in direct (but not mediated) ET. The advantages and drawbacks of the studied HRP-electrode systems for the electroanalytical detection of H 2 O 2 are considered.

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Glucose and Glutamate Detection by Oxidase/Hemin Peroxidase Mimic Cascades Assembled on Macro‐ and Microelectrodes

Lopes,

Kaewjua,

Shipovskov

et al. 2024

ChemElectroChem

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Enzymatic cascades are routinely used for electroanalysis of redox inactive species that can be enzymatically converted into species electroactive at moderate potentials, such as H2O2 produced by FAD‐dependent oxidases oxidising their substrates by O2. However, such cascades adaptation to micro‐biosensors is limited by enhanced mass‐transfer of produced H2O2 into solution, not to the sensing layer. Here, bi‐enzyme sensors for glucose or glutamate, produced by cross‐linking peroxidase and oxidases on carbon‐nanotube‐modified graphite macro‐electrodes (Gr), showed the from 0.1 to 10 mM glucose/glutamate linear response, while bio‐modified 5 μm carbon fibre electrodes (CFE) were mute due to fast transfer of enzymatically produced H2O2 into solution. By replacing peroxidase with peroxidase‐mimicking hemin in polyethyleneimine, the sensitivity of detection at Gr improved 3‐fold, enabling 2.8 μM glucose and 4.5 μM glutamate limits of detection, but not at CFE. Fast mass‐transfer of H2O2 from CFE to solution was restricted by the Nafion membrane facilitating glucose detection at CFE with a sensitivity of 1.67 A cm−2 M−1, at −0.6 V, escaping interference from other brain‐fluid components, redox‐inactive at this potential. Such membrane‐restricted cascade system provides the analytical access to a large group of enzymes that can be integrated in multiple enzymatic cascades for biosensing at microelectrodes.

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Effect of pH on direct electron transfer between graphite and horseradish peroxidase

Cited by 47 publications

References 26 publications

Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

Bioelectrocatalytical Detection of H₂O₂ with Different Forms of Horseradish Peroxidase Directly Adsorbed at Polycrystalline Silver and Gold

Glucose and Glutamate Detection by Oxidase/Hemin Peroxidase Mimic Cascades Assembled on Macro‐ and Microelectrodes

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Effect of pH on direct electron transfer between graphite and horseradish peroxidase

Cited by 47 publications

References 26 publications

Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

Bioelectrocatalysis of Plant Peroxidases Immobilized on Graphite in Aqueous and Mixed Solvent Media

Bioelectrocatalytical Detection of H2O2 with Different Forms of Horseradish Peroxidase Directly Adsorbed at Polycrystalline Silver and Gold

Glucose and Glutamate Detection by Oxidase/Hemin Peroxidase Mimic Cascades Assembled on Macro‐ and Microelectrodes

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Product

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Bioelectrocatalytical Detection of H₂O₂ with Different Forms of Horseradish Peroxidase Directly Adsorbed at Polycrystalline Silver and Gold