title: Direct electrochemistry and electrocatalysis of heme proteins entrapped in agarose hydrogel films in room-temperature ionic liquids.
abstract: The electrochemistry and electrocatalysis of a number of heme proteins entrapped in agarose hydrogel films in the room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) have been investigated. UV-vis and FTIR spectroscopy show that the heme proteins retain their native structure in agarose film. The uniform distribution of hemoglobin in agarose-dimethylformamide film was demonstrated by atomic force microscopy. Cyclic voltammetry shows that direct electron transfer between the heme proteins and glassy carbon electrode is quasi-reversible in [bmim][PF(6)]. The redox potentials for hemoglobin, myoglobin, horseradish peroxidase, cytochrome c, and catalase were found to be more negative than those in aqueous solution. The charge-transfer coefficient and the apparent electron-transfer rate constant for these heme proteins in [bmim][PF(6)] were calculated from the peak-to-peak separation as a function of scan rate. The heme proteins catalyze the electroreduction of trichloroacetic acid and tert-butyl hydroperoxide in [bmim][PF(6)]. The kinetic parameter I(max) (maximum current at saturation concentration of substrate) and the apparent K(m) (Michaelis-Menten constant) for the electrocatalytic reactions were evaluated.
authors.affiliation: College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China.
authors.forename: Sheng-Fu
authors.initials: SF
authors.lastname: Wang
authors.forename: Ting
authors.initials: T
authors.lastname: Chen
authors.forename: Zhi-Ling
authors.initials: ZL
authors.lastname: Zhang
authors.forename: Xin-Cheng
authors.initials: XC
authors.lastname: Shen
authors.forename: Zhe-Xue
authors.initials: ZX
authors.lastname: Lu
authors.forename: Dai-Wen
authors.initials: DW
authors.lastname: Pang
authors.forename: Kwok-Yin
authors.initials: KY
authors.lastname: Wong
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002384:Catalysis; D004563:Electrochemistry; D004566:Electrodes; D004579:Electron Transport; D006420:Hemeproteins / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D012685:Sepharose / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014238:Trichloroacetic Acid / Q000737:chemistry; D014867:Water / Q000737:chemistry; D020122:tert-Butylhydroperoxide / Q000737:chemistry
chemical_list: D006420:Hemeproteins; D020100:Hydrogels; D014867:Water; D014238:Trichloroacetic Acid; D012685:Sepharose; D020122:tert-Butylhydroperoxide