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Peroxide-dependent analyte conversion by the heme prosthetic group, the heme Peptide "microperoxidase-11" and cytochrome C on chitosan capped gold nanoparticles modified electrodes.

Yarman A, Neumann B, Bosserdt M, Gajovic-Eichelmann N, Scheller FW - Biosensors (Basel) (2012)

Bottom Line: In view of the role ascribed to the peroxidatic activity of degradation products of cytochrome c (cyt c) in the processes of apoptosis, we investigate the catalytic potential of heme and of the cyt c derived heme peptide MP-11 to catalyse the cathodic reduction of hydrogen peroxide and to oxidize aromatic compounds.The electrochemical signal for the peroxide reduction is generated by the redox conversion of the heme group, whilst a reaction product of the substrate oxidation is cathodically reduced in the substrate indication.The peroxidatic activity of cyt c immobilized in the chitosan layer for catechol was found to be below 1 per mill and for p-aminophenol about 3% as compared with that of heme or MP-11.

View Article: PubMed Central - PubMed

Affiliation: Fraunhofer Institute for Biomedical Engineering, IBMT, D-14476 Potsdam, Germany. aysu.yarman@yahoo.de.

ABSTRACT
In view of the role ascribed to the peroxidatic activity of degradation products of cytochrome c (cyt c) in the processes of apoptosis, we investigate the catalytic potential of heme and of the cyt c derived heme peptide MP-11 to catalyse the cathodic reduction of hydrogen peroxide and to oxidize aromatic compounds. In order to check whether cyt c has an enzymatic activity in the native state where the protein matrix should suppress the inherent peroxidatic activity of its heme prosthetic group, we applied a biocompatible immobilization matrix and very low concentrations of the co-substrate H2O2. The biocatalysts were entrapped on the surface of a glassy carbon electrode in a biocompatible chitosan layer which contained gold nanoparticles. The electrochemical signal for the peroxide reduction is generated by the redox conversion of the heme group, whilst a reaction product of the substrate oxidation is cathodically reduced in the substrate indication. The catalytic efficiency of microperoxidase-11 is sufficient for sensors indicating HRP substrates, e.g., p-aminophenol, paracetamol and catechol, but also the hydroxylation of aniline and dehalogenation of 4-fluoroaniline. The lower limit of detection for p-aminophenol is comparable to previously published papers with different enzyme systems. The peroxidatic activity of cyt c immobilized in the chitosan layer for catechol was found to be below 1 per mill and for p-aminophenol about 3% as compared with that of heme or MP-11.

No MeSH data available.


Formal potentials of MP-11 immobilized in a matrix of chitosan embedded AuNPs at GCE at pHs between 5 and 7 at 100 mV/s.
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biosensors-02-00189-f004: Formal potentials of MP-11 immobilized in a matrix of chitosan embedded AuNPs at GCE at pHs between 5 and 7 at 100 mV/s.

Mentions: Figure 4 shows the effect of pH in 10 mM phosphate buffer on the DET of MP-11-AuNP-CH/GCE at 100 mV/s. The formal potentials (E0’) of MP-11 in the gold nanoparticles-chitosan film were determined in the pH interval between 5 and 7. They are shifted in anodic direction by almost 89 mV at pH 5 as compared with the value at pH 7. This behavior is in accordance with the pH dependence of the redox potential of microperoxidases in the literature which ascribes the potential shift at pH 5 to the dissociation of the propionic side chain of the heme [22]. The slope of the line dE/dpH was calculated to be −43.8 which is close to one electron/ one proton transfer. The positions of peaks and of the formal potentials are comparable to previously published data for the Fe2+/Fe3+ redox couple of MPs [23,24].


Peroxide-dependent analyte conversion by the heme prosthetic group, the heme Peptide "microperoxidase-11" and cytochrome C on chitosan capped gold nanoparticles modified electrodes.

Yarman A, Neumann B, Bosserdt M, Gajovic-Eichelmann N, Scheller FW - Biosensors (Basel) (2012)

Formal potentials of MP-11 immobilized in a matrix of chitosan embedded AuNPs at GCE at pHs between 5 and 7 at 100 mV/s.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263574&req=5

biosensors-02-00189-f004: Formal potentials of MP-11 immobilized in a matrix of chitosan embedded AuNPs at GCE at pHs between 5 and 7 at 100 mV/s.
Mentions: Figure 4 shows the effect of pH in 10 mM phosphate buffer on the DET of MP-11-AuNP-CH/GCE at 100 mV/s. The formal potentials (E0’) of MP-11 in the gold nanoparticles-chitosan film were determined in the pH interval between 5 and 7. They are shifted in anodic direction by almost 89 mV at pH 5 as compared with the value at pH 7. This behavior is in accordance with the pH dependence of the redox potential of microperoxidases in the literature which ascribes the potential shift at pH 5 to the dissociation of the propionic side chain of the heme [22]. The slope of the line dE/dpH was calculated to be −43.8 which is close to one electron/ one proton transfer. The positions of peaks and of the formal potentials are comparable to previously published data for the Fe2+/Fe3+ redox couple of MPs [23,24].

Bottom Line: In view of the role ascribed to the peroxidatic activity of degradation products of cytochrome c (cyt c) in the processes of apoptosis, we investigate the catalytic potential of heme and of the cyt c derived heme peptide MP-11 to catalyse the cathodic reduction of hydrogen peroxide and to oxidize aromatic compounds.The electrochemical signal for the peroxide reduction is generated by the redox conversion of the heme group, whilst a reaction product of the substrate oxidation is cathodically reduced in the substrate indication.The peroxidatic activity of cyt c immobilized in the chitosan layer for catechol was found to be below 1 per mill and for p-aminophenol about 3% as compared with that of heme or MP-11.

View Article: PubMed Central - PubMed

Affiliation: Fraunhofer Institute for Biomedical Engineering, IBMT, D-14476 Potsdam, Germany. aysu.yarman@yahoo.de.

ABSTRACT
In view of the role ascribed to the peroxidatic activity of degradation products of cytochrome c (cyt c) in the processes of apoptosis, we investigate the catalytic potential of heme and of the cyt c derived heme peptide MP-11 to catalyse the cathodic reduction of hydrogen peroxide and to oxidize aromatic compounds. In order to check whether cyt c has an enzymatic activity in the native state where the protein matrix should suppress the inherent peroxidatic activity of its heme prosthetic group, we applied a biocompatible immobilization matrix and very low concentrations of the co-substrate H2O2. The biocatalysts were entrapped on the surface of a glassy carbon electrode in a biocompatible chitosan layer which contained gold nanoparticles. The electrochemical signal for the peroxide reduction is generated by the redox conversion of the heme group, whilst a reaction product of the substrate oxidation is cathodically reduced in the substrate indication. The catalytic efficiency of microperoxidase-11 is sufficient for sensors indicating HRP substrates, e.g., p-aminophenol, paracetamol and catechol, but also the hydroxylation of aniline and dehalogenation of 4-fluoroaniline. The lower limit of detection for p-aminophenol is comparable to previously published papers with different enzyme systems. The peroxidatic activity of cyt c immobilized in the chitosan layer for catechol was found to be below 1 per mill and for p-aminophenol about 3% as compared with that of heme or MP-11.

No MeSH data available.