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Direct heterogeneous electron transfer of theophylline oxidase

Christenson, Andreas LU ; Dock, Eva LU ; Gorton, Lo LU and Ruzgas, Tautgirdas LU (2004) In Biosensors & Bioelectronics 20(2). p.176-183
Abstract
Direct electron transfer (DET) was shown between the heme containing enzyme theophylline oxidase (ThO) and the surface of both graphite and gold electrodes. As proof on graphite a steady state current for theophylline was recorded using the electrode modified with adsorbed ThO. The electrode showed a Michaelis–Menten-like response to theophylline with a detection limit of 0.2 mM and a Michaelis–Menten constant equal to 3.2 mM. These initial results open up a possibility for the development of reagentless third generation biosensor based on heterogeneous DET between ThO and an electrode. On gold DET between ThO and the surface of aldrithiol modified gold was studied with spectroelectrochemical measurements. DET was observed for soluble ThO... (More)
Direct electron transfer (DET) was shown between the heme containing enzyme theophylline oxidase (ThO) and the surface of both graphite and gold electrodes. As proof on graphite a steady state current for theophylline was recorded using the electrode modified with adsorbed ThO. The electrode showed a Michaelis–Menten-like response to theophylline with a detection limit of 0.2 mM and a Michaelis–Menten constant equal to 3.2 mM. These initial results open up a possibility for the development of reagentless third generation biosensor based on heterogeneous DET between ThO and an electrode. On gold DET between ThO and the surface of aldrithiol modified gold was studied with spectroelectrochemical measurements. DET was observed for soluble ThO as a change of its spectrum in a gold capillary responding to a change in the applied potential. It was shown that the redox conversion of the heme domain of the enzyme is directly (mediatorlessly) driven by the potential applied at the gold electrode. The measurements enabled an estimation of the formal potential (E°′) of the redox process equal to −275±50 mV versus Ag|AgClsat at pH 7.0. The experimentally determined number of the electrons involved in this heterogeneous electron transfer process was estimated to be equal to 0.53. The low precision in determination of the E°′ and the value of the number of electrons lower than one indicate that kinetic restrictions disturbed the evaluation of the true thermodynamic values from relatively fast spectroelectrochemical measurements.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biosensors & Bioelectronics
volume
20
issue
2
pages
176 - 183
publisher
Elsevier
external identifiers
  • wos:000224034400006
  • pmid:15308219
  • scopus:4043137139
ISSN
1873-4235
DOI
10.1016/j.bios.2004.03.010
language
English
LU publication?
yes
id
f53d3c05-ba7b-4d40-ad6f-be729748819a (old id 135530)
date added to LUP
2007-06-26 13:33:10
date last changed
2017-06-11 04:26:53
@article{f53d3c05-ba7b-4d40-ad6f-be729748819a,
  abstract     = {Direct electron transfer (DET) was shown between the heme containing enzyme theophylline oxidase (ThO) and the surface of both graphite and gold electrodes. As proof on graphite a steady state current for theophylline was recorded using the electrode modified with adsorbed ThO. The electrode showed a Michaelis–Menten-like response to theophylline with a detection limit of 0.2 mM and a Michaelis–Menten constant equal to 3.2 mM. These initial results open up a possibility for the development of reagentless third generation biosensor based on heterogeneous DET between ThO and an electrode. On gold DET between ThO and the surface of aldrithiol modified gold was studied with spectroelectrochemical measurements. DET was observed for soluble ThO as a change of its spectrum in a gold capillary responding to a change in the applied potential. It was shown that the redox conversion of the heme domain of the enzyme is directly (mediatorlessly) driven by the potential applied at the gold electrode. The measurements enabled an estimation of the formal potential (E°′) of the redox process equal to −275±50 mV versus Ag|AgClsat at pH 7.0. The experimentally determined number of the electrons involved in this heterogeneous electron transfer process was estimated to be equal to 0.53. The low precision in determination of the E°′ and the value of the number of electrons lower than one indicate that kinetic restrictions disturbed the evaluation of the true thermodynamic values from relatively fast spectroelectrochemical measurements. <br/><br>
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This is the final, accepted and revised manuscript of this article. Use alternative location to go to the published article. Requires subscription.},
  author       = {Christenson, Andreas and Dock, Eva and Gorton, Lo and Ruzgas, Tautgirdas},
  issn         = {1873-4235},
  language     = {eng},
  number       = {2},
  pages        = {176--183},
  publisher    = {Elsevier},
  series       = {Biosensors & Bioelectronics},
  title        = {Direct heterogeneous electron transfer of theophylline oxidase},
  url          = {http://dx.doi.org/10.1016/j.bios.2004.03.010},
  volume       = {20},
  year         = {2004},
}