Electrochemistry Of Catalase And Its Mimic

The use of electrochemical techniques to study redox proteins and their activesites has gained increasing attention. Electrochemical methods can be used to extract essential physicochemical data concerning energetics of protein redox reaction and to study mechanisms of electron transfer in metalloproteins. Direct electrochemistry of proteins or enzymes has potential application in fabricating electrochemical biosensors, which combine the speciality of biological recognition element with the advantages of electrochemical methods such as higher sensitivity and operation in situ.In the thesis, the electrochemistry and electrocatalysis of catalase and hematin immobilized on electrode surface by agarose hydrogel are investigated:A pair of well-defined and quasi-reversible redox peaks both in aqueous buffer and ethanol-aqueous mixture was obtained. The formal potential (E^o') indicates the reactions origin from the direct electron transfer between E-Fe(â…¢)/(â…¡) couple and the electrode surface. The E^o' is linearly dependent on solution pH (redox Bohr effect), indicating the electron transfer of E-Fe(â…¢)/(â…¡) redox couple accompanied with the transfer of a proton.The electron transfer can be facilitated in ethanol-aqueous mixture for the reason of partial dehydration of the distal heme pocket. The water pools in agarose hydrogel play an important role in preventing either the change of conformation or the inactivity of Cat from polar organic solvent. Cat retains its original conformation in the agarose film that was confirmed by UV-Vis spectra and electrochemical behaviors in comparison to the controlled experiments using free hemin. The Catalytic reactions to peroxides (hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide, 2-butanone peroxide) using Cat-agarose modified electrode were also explored both in aqueous buffer and ethanol-aqueous mixture. The hematin-agarose modified electrode have the similar electrochemistry and electrocatalysis.The method could be application to the preparation of the hydrogel based third generation biosensors in organic media.