title: Recombinant horseradish peroxidase - and cytochrome c-based two-electrode system for detection of superoxide radicals.
abstract: The reliable detection of a superoxide anion radical O2(*-) is complicated by its spontaneous dismutation reaction to H2O2 at acidic pHs. To simultaneously detect both O2(*-) and H2O2 produced in the course of its spontaneous dismutation, an electrochemical two-electrode system based on cytochrome c (cyt c) and recombinant horseradish peroxidase (rHRP) was applied. Therewith, a limited applicability of the cyt c system for the reliable monitoring of O2(*-) in acidic and neutral solutions was shown. It was demonstrated that both the reaction of O2(*-) dismutation to H2O2 and the reaction between the formed H2O2 and O2(*-) chemically decrease the amount of the initially present O2(*-), decreasing the sensitivity and reliability of the electrochemical detection at acidic pH. However, by appropriately varying solution pH, the concentration of O2(*-) initially injected in the system can be estimated from the analysis of calibration curves for H2O2 obtained with highly sensitive rHRP-modified electrode system at pH 6.0 and 7.0.
authors.affiliation: Department of Molecular Biophysics, Lund University, P.O. Box 124, Lund SE 22100, Sweden.
authors.forename: Stepan
authors.initials: S
authors.lastname: Shipovskov
authors.forename: Elena E
authors.initials: EE
authors.lastname: Ferapontova
authors.forename: Irina
authors.initials: I
authors.lastname: Gazaryan
authors.forename: Tautgirdas
authors.initials: T
authors.lastname: Ruzgas
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D045304:Cytochromes c / Q000032:analysis / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D006735:Horseradish Peroxidase / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D006861:Hydrogen Peroxide / Q000032:analysis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D011994:Recombinant Proteins / Q000032:analysis / Q000737:chemistry; D013481:Superoxides / Q000032:analysis* / Q000737:chemistry*
chemical_list: D011994:Recombinant Proteins; D013481:Superoxides; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase