Direct electrochemistry and electrocatalysis of heme proteins entrapped in agarose hydrogel films in room-temperature ionic liquids

Langmuir. 2005 Sep 27;21(20):9260-6. doi: 10.1021/la050947k.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biosensing Techniques / methods*
  • Catalysis
  • Electrochemistry
  • Electrodes
  • Electron Transport
  • Hemeproteins / chemistry*
  • Hydrogels / chemistry*
  • Kinetics
  • Oxidation-Reduction
  • Sepharose / chemistry*
  • Spectrophotometry, Ultraviolet
  • Spectroscopy, Fourier Transform Infrared
  • Temperature
  • Trichloroacetic Acid / chemistry
  • Water / chemistry
  • tert-Butylhydroperoxide / chemistry

Substances

  • Hemeproteins
  • Hydrogels
  • Water
  • Trichloroacetic Acid
  • Sepharose
  • tert-Butylhydroperoxide