%0 Journal Article
%T Peroxide-Dependent Analyte Conversion by the Heme Prosthetic Group, the Heme Peptide ¡°Microperoxidase-11¡± and Cytochrome c on Chitosan Capped Gold Nanoparticles Modified Electrodes
%A Aysu Yarman
%A Bettina Neumann
%A Maria Bosserdt
%A Nenad Gajovic-Eichelmann
%A Frieder W. Scheller
%J Biosensors
%D 2012
%I MDPI AG
%R 10.3390/bios2020189
%X 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 H 2O 2. 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.
%K peroxide dependent catalysis
%K hemin
%K microperoxidase-11
%K cytochrome c
%U http://www.mdpi.com/2079-6374/2/2/189