Electrochemically mediated reduction of horseradish peroxidase by 1,1′-ferrocenedimethanol in organic solvents

Anastassija Konash, Edmond Magner

Research output: Contribution to journalArticlepeer-review

Abstract

Cyclic voltammetry is an efficient means of analyzing the catalytic reduction of H2O2 at immobilized horseradish peroxidase (HRP)-Eastman AQ 55 electrodes in the presence of 1,1′-ferrocenedimethanol as a one-electron reversible cosubstrate. This system was employed to study the kinetics of the reduction of compound II of HRP in a number of organic solvents. An electrocatalytic response was detected in methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, 2-butanone, 1,2-propanediol, acetonitrile, ethyl acetate, and ethylene glycol. Unusual bell-shaped variations of the peak or plateau catalytic current with the substrate concentration were observed in all solvents tested. The results obtained in methanol, acetonitrile, and 1-propanol were analyzed using the model developed by Saveant (Limoges, B.; Saveant, J.-M.; Yazidi, D. J. Am. Chem. Soc. 2003, 125, 9192-9203). The values of k3Γ0 and K3,M, where k3 = k3,1k3,2/(k3,-1 + k3,2), Γ0 is the surface concentration of active enzyme, and K 3,M = (k3,-1 + k3,2)/k3,1, were determined. The values of k3Γ0 for the mediated reduction of compound II of HRP in methanol, 1-propanol, and acetonitrile (in the presence of 5% aqueous buffer) were not affected by the solvent dielectric constant but decreased with solvent hydrophobicity. The value of K3,M obtained in methanol was similar to that obtained for [Os-(bpy) 2pyCl]2+ in aqueous buffer.

Original languageEnglish
Pages (from-to)1647-1654
Number of pages8
JournalAnalytical Chemistry
Volume77
Issue number6
DOIs
Publication statusPublished - 15 Mar 2005

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