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Bilirubin Oxidase from Myrothecium verrucaria Physically Absorbed on Graphite Electrodes. Insights into the Alternative Resting Form and the Sources of Activity Loss.

Tasca F, Farias D, Castro C, Acuna-Rougier C, Antiochia R - PLoS ONE (2015)

Bottom Line: The oxygen reduction reaction is one of the most important chemical processes in energy converting systems and living organisms.The existence of an alternative resting form of the enzyme is validated.The effect on the catalytic cycle of temperature, pH and the presence of halogens in the buffer was investigated.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, RM, Chile.

ABSTRACT
The oxygen reduction reaction is one of the most important chemical processes in energy converting systems and living organisms. Mediator-less, direct electro-catalytic reduction of oxygen to water was achieved on spectrographite electrodes modified by physical adsorption of bilirubin oxidases from Myrothecium verrucaria. The existence of an alternative resting form of the enzyme is validated. The effect on the catalytic cycle of temperature, pH and the presence of halogens in the buffer was investigated. Previous results on the electrochemistry of bilirubin oxidase and on the impact of the presence of halogens are reviewed and reinterpreted.

No MeSH data available.


Chronoamperometric trace for MvBOD on SPGE.After 1000s NaCl for a final concentration of 0.1 M was added. Sodium phosphate (0.1 M) buffer, pH 7. Electrode set at 600 mV vs. NHE.
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pone.0132181.g006: Chronoamperometric trace for MvBOD on SPGE.After 1000s NaCl for a final concentration of 0.1 M was added. Sodium phosphate (0.1 M) buffer, pH 7. Electrode set at 600 mV vs. NHE.

Mentions: Chloride inhibition has been debated and contrasting results have been presented [15]. If a device has to be implanted in animals (i.e., implantable biofuel cells) the presence of chloride has to be taken into account. Early studies conducted by Heller and co-workers found very weak Cl- inhibition of BODs when these were immobilized on electrodes in the presence of Os-redox polymers [24–26]. For immobilized MCOs, in direct electron transfer with the electrode, different results have been obtained with respect to Cl−inhibition. In a study by Blanford et al., T.versicolor laccase lost more than 50% of its activity in the presence of 25 mM NaCl [27] when immobilized on an anthracene-modified graphite electrode. In contrast, Vaz-Dominguez et al. found practically no inhibition of T. hirsuta laccase, with NaCl > 350 mM [28]. Fig 6 shows chronoamperometry measurements for oxygen reduction with the electrode poisoned at 600 mV.


Bilirubin Oxidase from Myrothecium verrucaria Physically Absorbed on Graphite Electrodes. Insights into the Alternative Resting Form and the Sources of Activity Loss.

Tasca F, Farias D, Castro C, Acuna-Rougier C, Antiochia R - PLoS ONE (2015)

Chronoamperometric trace for MvBOD on SPGE.After 1000s NaCl for a final concentration of 0.1 M was added. Sodium phosphate (0.1 M) buffer, pH 7. Electrode set at 600 mV vs. NHE.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4510396&req=5

pone.0132181.g006: Chronoamperometric trace for MvBOD on SPGE.After 1000s NaCl for a final concentration of 0.1 M was added. Sodium phosphate (0.1 M) buffer, pH 7. Electrode set at 600 mV vs. NHE.
Mentions: Chloride inhibition has been debated and contrasting results have been presented [15]. If a device has to be implanted in animals (i.e., implantable biofuel cells) the presence of chloride has to be taken into account. Early studies conducted by Heller and co-workers found very weak Cl- inhibition of BODs when these were immobilized on electrodes in the presence of Os-redox polymers [24–26]. For immobilized MCOs, in direct electron transfer with the electrode, different results have been obtained with respect to Cl−inhibition. In a study by Blanford et al., T.versicolor laccase lost more than 50% of its activity in the presence of 25 mM NaCl [27] when immobilized on an anthracene-modified graphite electrode. In contrast, Vaz-Dominguez et al. found practically no inhibition of T. hirsuta laccase, with NaCl > 350 mM [28]. Fig 6 shows chronoamperometry measurements for oxygen reduction with the electrode poisoned at 600 mV.

Bottom Line: The oxygen reduction reaction is one of the most important chemical processes in energy converting systems and living organisms.The existence of an alternative resting form of the enzyme is validated.The effect on the catalytic cycle of temperature, pH and the presence of halogens in the buffer was investigated.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, RM, Chile.

ABSTRACT
The oxygen reduction reaction is one of the most important chemical processes in energy converting systems and living organisms. Mediator-less, direct electro-catalytic reduction of oxygen to water was achieved on spectrographite electrodes modified by physical adsorption of bilirubin oxidases from Myrothecium verrucaria. The existence of an alternative resting form of the enzyme is validated. The effect on the catalytic cycle of temperature, pH and the presence of halogens in the buffer was investigated. Previous results on the electrochemistry of bilirubin oxidase and on the impact of the presence of halogens are reviewed and reinterpreted.

No MeSH data available.