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Direct electron transfer of heme- and molybdopterin cofactor-containing chicken liver sulfite oxidase on alkanethiol-modified gold electrodes

Ferapontova, Elena LU ; Ruzgas, Tautgirdas LU and Gorton, Lo LU (2003) In Analytical Chemistry 75(18). p.4841-4850
Abstract
Direct heterogeneous electron transfer (ET) of sulfite oxidase (SOx), a heme- and molybdopterin cofactor-containing intermembrane enzyme, was studied on alkanethiol-modified Au electrodes both with SOx entrapped between the modified Au electrode and a permselective membrane and with SOx adsorbed at the electrode surface, in the absence of any membrane. SOx in direct electronic communication with the electrode surface gave a quasi-reversible electrochemical signal with a midpoint potential of -120 mV vs Ag AgCl corresponding to the redox transformations of the heme domain of SOx and with a heterogeneous ET constant in the order of 15 s-1. The efficiency of the bioelectrocatalytic 2e- oxidation of sulfite catalyzed by SOx in direct ET... (More)
Direct heterogeneous electron transfer (ET) of sulfite oxidase (SOx), a heme- and molybdopterin cofactor-containing intermembrane enzyme, was studied on alkanethiol-modified Au electrodes both with SOx entrapped between the modified Au electrode and a permselective membrane and with SOx adsorbed at the electrode surface, in the absence of any membrane. SOx in direct electronic communication with the electrode surface gave a quasi-reversible electrochemical signal with a midpoint potential of -120 mV vs Ag AgCl corresponding to the redox transformations of the heme domain of SOx and with a heterogeneous ET constant in the order of 15 s-1. The efficiency of the bioelectrocatalytic 2e- oxidation of sulfite catalyzed by SOx in direct ET exchange with the electrode was shown to depend essentially on the nature of the alkanethiol layer. Adsorption and orientation of SOx on an 11-mercapto-1-undecanol (MuD-OH) self-assembled monolayer, i.e., terminally functionalized with OH groups, provided efficient catalytic oxidation of sulfite, contrary to nonfunctionalized alkanethiols, e.g., 1-decanethiol, or alkanethiol layers terminally functionalized with NH2 groups. Comparative studies with short-chain alkanethiols, e.g., cysteamine and 2-mercaptoethanol, revealed an evidently different mode of adsorption of SOx on these layers, onto which SOx was not catalytically active. Coadsorption of MuD-OH and 11-mercapto-1-undecanamine improved the surface properties of the SAM, resulting in a higher surface coverage with bioelectrocatalytically active SOx but not in an increased apparent catalytic rate constant, kcat, ranging in the order of 18-24 s-1 at pH 7.4. The achieved efficiency of SOx bioelectrocatalysis in direct ET reaction between the modified electrode and the enzyme approached the rates characteristic for the catalysis mediated by cytochrome c, the natural redox partner of SOx, thus implying the retention of the biological function of SOx under the heterogeneous electrode reaction conditions. Results obtained enable the development of a third-generation biosensor for sulfite monitoring. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Analytical Chemistry
volume
75
issue
18
pages
4841 - 4850
publisher
The American Chemical Society
external identifiers
  • wos:000185439300018
  • pmid:14674462
  • scopus:0141482219
ISSN
1520-6882
DOI
10.1021/ac0341923
language
English
LU publication?
yes
id
13181718-9877-4f6a-bd32-d7009cf09d30 (old id 128894)
date added to LUP
2007-06-26 15:58:31
date last changed
2018-10-03 10:21:53
@article{13181718-9877-4f6a-bd32-d7009cf09d30,
  abstract     = {Direct heterogeneous electron transfer (ET) of sulfite oxidase (SOx), a heme- and molybdopterin cofactor-containing intermembrane enzyme, was studied on alkanethiol-modified Au electrodes both with SOx entrapped between the modified Au electrode and a permselective membrane and with SOx adsorbed at the electrode surface, in the absence of any membrane. SOx in direct electronic communication with the electrode surface gave a quasi-reversible electrochemical signal with a midpoint potential of -120 mV vs Ag AgCl corresponding to the redox transformations of the heme domain of SOx and with a heterogeneous ET constant in the order of 15 s-1. The efficiency of the bioelectrocatalytic 2e- oxidation of sulfite catalyzed by SOx in direct ET exchange with the electrode was shown to depend essentially on the nature of the alkanethiol layer. Adsorption and orientation of SOx on an 11-mercapto-1-undecanol (MuD-OH) self-assembled monolayer, i.e., terminally functionalized with OH groups, provided efficient catalytic oxidation of sulfite, contrary to nonfunctionalized alkanethiols, e.g., 1-decanethiol, or alkanethiol layers terminally functionalized with NH2 groups. Comparative studies with short-chain alkanethiols, e.g., cysteamine and 2-mercaptoethanol, revealed an evidently different mode of adsorption of SOx on these layers, onto which SOx was not catalytically active. Coadsorption of MuD-OH and 11-mercapto-1-undecanamine improved the surface properties of the SAM, resulting in a higher surface coverage with bioelectrocatalytically active SOx but not in an increased apparent catalytic rate constant, kcat, ranging in the order of 18-24 s-1 at pH 7.4. The achieved efficiency of SOx bioelectrocatalysis in direct ET reaction between the modified electrode and the enzyme approached the rates characteristic for the catalysis mediated by cytochrome c, the natural redox partner of SOx, thus implying the retention of the biological function of SOx under the heterogeneous electrode reaction conditions. Results obtained enable the development of a third-generation biosensor for sulfite monitoring.},
  author       = {Ferapontova, Elena and Ruzgas, Tautgirdas and Gorton, Lo},
  issn         = {1520-6882},
  language     = {eng},
  number       = {18},
  pages        = {4841--4850},
  publisher    = {The American Chemical Society},
  series       = {Analytical Chemistry},
  title        = {Direct electron transfer of heme- and molybdopterin cofactor-containing chicken liver sulfite oxidase on alkanethiol-modified gold electrodes},
  url          = {http://dx.doi.org/10.1021/ac0341923},
  volume       = {75},
  year         = {2003},
}