title: Direct voltammetry and electrocatalytic properties of catalase incorporated in polyacrylamide hydrogel films.
abstract: The direct voltammetry and electrocatalytic properties of catalase (Cat) in polyacrylamide (PAM) hydrogel films cast on pyrolytic graphite (PG) electrodes were investigated. Cat-PAM film electrodes showed a pair of well-defined and nearly reversible cyclic voltammetry peaks for Cat Fe(III)/Fe(II) redox couples at approximately -0.46 V vs. SCE in pH 7.0 buffers. The electron transfer between catalase and PG electrodes was greatly facilitated in the microenvironment of PAM films. The apparent heterogeneous electron transfer rate constant (k(s)) and formal potential (E degrees ') were estimated by fitting square wave voltammograms with non-linear regression analysis. The formal potential of Cat Fe(III)/Fe(II) couples in PAM films had a linear relationship with pH between pH 4.0 and 9.0 with a slope of -56 mV pH(-1), suggesting that one proton is coupled with single-electron transfer for each heme group of catalase in the electrode reaction. UV-Vis absorption spectroscopy demonstrated that catalase retained a near native conformation in PAM films at medium pH. The embedded catalase in PAM films showed the electrocatalytic activity toward dioxygen and hydrogen peroxide. Possible mechanism of catalytic reduction of H(2)O(2) at Cat-PAM film electrodes was proposed.
authors.affiliation: Department of Chemistry, Beijing Normal University, Beijing 100875, PR China.
authors.forename: Haiyun
authors.initials: H
authors.lastname: Lu
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.forename: Naifei
authors.initials: N
authors.lastname: Hu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D015374:Biosensing Techniques; D002244:Carbon / Q000737:chemistry; D002374:Catalase / Q000737:chemistry* / Q000378:metabolism; D002384:Catalysis; D002417:Cattle; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry; D048271:Chitosan; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D004563:Electrochemistry; D004579:Electron Transport; D006454:Hemoglobins / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000201:enzymology; D008855:Microscopy, Electron, Scanning; D009211:Myoglobin / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013057:Spectrum Analysis
chemical_list: D000180:Acrylic Resins; D006454:Hemoglobins; D009211:Myoglobin; D000644:Quaternary Ammonium Compounds; C016680:polyacrylamide gels; C009139:pyrolytic carbon; C046112:didodecyldimethylammonium; D002686:Chitin; D002244:Carbon; D048271:Chitosan; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D002374:Catalase; D010100:Oxygen; D004134:Dimyristoylphosphatidylcholine