Bioelectrocatalytic Oxygen Reaction and Chloride Inhibition Resistance of Laccase Immobilized on Single-walled Carbon Nanotube and Carbon Paper Electrodes

Tominaga, Masato; Sasaki, Aiko; Togami, Makoto

doi:10.5796/electrochemistry.84.315

Cited by 10 publications

(26 citation statements)

References 32 publications

(61 reference statements)

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“…Figure 5D shows cyclic voltammetry of the BOD reactivation at pH 7 without inhibitor, where it is possible to displace F − , recovering 95% of the activity. These results are in agreement with those published by other authors, which suggest that F − ions inhibit DET and MET [55][56][57]. Another halide that inhibits the BOD is Cl − .…”

Section: Inhibitory Effectsupporting

confidence: 93%

“…After using a fresh buffer solution no hysteresis were observed. Cl − showed a competitive inhibition [56,57]. Nevertheless, the inhibition process occurred only during DET and at very high concentrations of NaCl (>0.1 M).…”

Section: Discussionmentioning

confidence: 94%

“…However, Jensen and co-workers [59] have witnessed the Cl − inhibition effect on laccase in DET. Nevertheless, high resistance to Cl − inhibition under DET has been reported in nanostructured electrodes, which suggests that they avoid Cl − entry to the T1 site [56,57]. The activity test was performed on each prepared batch and resulted to be 12 ± 2 U/mg whereas one unit is defined as the amount of enzyme that oxidizes 1 µmol of ABTS per minute.…”

Section: Inhibitory Effectmentioning

confidence: 99%

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Comparison of Direct and Mediated Electron Transfer for Bilirubin Oxidase from Myrothecium Verrucaria. Effects of Inhibitors and Temperature on the Oxygen Reduction Reaction

et al. 2019

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One of the processes most studied in bioenergetic systems in recent years is the oxygen reduction reaction (ORR). An important challenge in bioelectrochemistry is to achieve this reaction under physiological conditions. In this study, we used bilirubin oxidase (BOD) from Myrothecium verrucaria, a subclass of multicopper oxidases (MCOs), to catalyse the ORR to water via four electrons in physiological conditions. The active site of BOD, the T2/T3 cluster, contains three Cu atoms classified as T2, T3α, and T3β depending on their spectroscopic characteristics. A fourth Cu atom; the T1 cluster acts as a relay of electrons to the T2/T3 cluster. Graphite electrodes were modified with BOD and the direct electron transfer (DET) to the enzyme, and the mediated electron transfer (MET) using an osmium polymer (OsP) as a redox mediator, were compared. As a result, an alternative resting (AR) form was observed in the catalytic cycle of BOD. In the absence and presence of the redox mediator, the AR direct reduction occurs through the trinuclear site (TNC) via T1, specifically activated at low potentials in which T2 and T3α of the TNC are reduced and T3β is oxidized. A comparative study between the DET and MET was conducted at various pH and temperatures, considering the influence of inhibitors like H2O2, F−, and Cl−. In the presence of H2O2 and F−, these bind to the TNC in a non-competitive reversible inhibition of O2. Instead; Cl− acts as a competitive inhibitor for the electron donor substrate and binds to the T1 site.

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Section: Inhibitory Effectsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 94%

Section: Inhibitory Effectmentioning

confidence: 99%

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Comparison of Direct and Mediated Electron Transfer for Bilirubin Oxidase from Myrothecium Verrucaria. Effects of Inhibitors and Temperature on the Oxygen Reduction Reaction

et al. 2019

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“…Naki et al reported a kinetic study of Polyporus versicolor Lc showing that Cl − was a competitive inhibitor with respect to the electron donor substrate (ferrocyanide), thus suggesting that the Cl − was binding to or near the T1 site [10]. Furthermore, bioelectrocatalytic studies of Lcs have shown that direct electron transfer (DET) from the electrode to the enzyme is much less affected by Cl − than the mediated electron transfer (MET) using different substrates, whereas F − blocks both electron transfer modes [17][18][19][20]. This result was explained by considering that Cl − binds near the substrate binding site, precluding T1 reduction by the substrate but not electron transfer from the electrode.…”

mentioning

confidence: 99%

Halides inhibition of multicopper oxidases studied by FTIR spectroelectrochemistry using azide as an active infrared probe

et al. 2017

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An infrared spectroelectrochemical study of Trametes hirsuta laccase and Magnaporthe oryzae bilirubin oxidase has been performed using azide, an inhibitor of multicopper oxidases, as an active infrared probe incorporated into the T2/T3 copper cluster of the enzymes. The redox potential-controlled measurements indicate that N stretching IR bands of azide ion bound to the T2/T3 cluster are only detected for the oxidized enzymes, confirming that azide only binds to Cu. Moreover, the process of binding/dissociation of azide ion is shown to be reversible. The interaction of halide anions, which also inhibit multicopper oxidases, with the active site of the enzymes was studied by measuring the changes in the azide FTIR bands. Enzymes inhibited by azide respond differently upon addition of fluoride or chloride ions to the sample solution inhibited by azide. Fluoride ions compete with azide for binding at one of the T2/T3 Cu ions, whereas competition from chloride ions is much less evident.

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“…SC molecules act as an insulating barrier and inhibit fast electron transfer when the SC molecules form a multilayer on the HOPG interface. The electron transfer rate constant (k˚') for Lac at the SC-modified HOPG was evaluated by previously reported methods [25][26][27]. Figure 7a shows the catalytic current steady-state voltammograms and their fittings with simulated plots (Supplementary Material).…”

Section: = (−2 )mentioning

confidence: 99%

Cholate Adsorption Behavior at Carbon Electrode Interface and Its Promotional Effect in Laccase Direct Bioelectrocatalysis

Tominaga¹,

Tsutsui²,

Takatori³

2018

Colloids and Interfaces

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Fast electron transfer between laccase (Lac) and single-walled carbon nanotubes (SWCNTs) can be achieved at a cholate-modified SWCNT interface. Furthermore, the catalytic reduction of O 2 starts at a high potential, close to the equilibrium redox potential of the O 2 /H 2 O couple. A sodium cholate (SC)-modified electrode interface provides suitable conditions for Lac direct bioelectrocatalysis. In the present study, the SC promotional effect in Lac direct bioelectrocatalysis was investigated using various types of electrode materials. The fully hydrophilic surface of indium tin oxide and an Au electrode surface did not show a SC promotional effect, because SC did not bind to these surfaces. A carbon surface with a large number of defects was unsuitable for SC binding because of hydrophilic functional groups at the defect sites. Carbon surfaces with few defects, for example, basal-plane highly oriented pyrolytic graphite (HOPG), gave a SC promotional effect.

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Bioelectrocatalytic Oxygen Reaction and Chloride Inhibition Resistance of Laccase Immobilized on Single-walled Carbon Nanotube and Carbon Paper Electrodes

Cited by 10 publications

References 32 publications

Comparison of Direct and Mediated Electron Transfer for Bilirubin Oxidase from Myrothecium Verrucaria. Effects of Inhibitors and Temperature on the Oxygen Reduction Reaction

Comparison of Direct and Mediated Electron Transfer for Bilirubin Oxidase from Myrothecium Verrucaria. Effects of Inhibitors and Temperature on the Oxygen Reduction Reaction

Halides inhibition of multicopper oxidases studied by FTIR spectroelectrochemistry using azide as an active infrared probe

Cholate Adsorption Behavior at Carbon Electrode Interface and Its Promotional Effect in Laccase Direct Bioelectrocatalysis

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