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Direct electron transfer kinetics in horseradish peroxidase electrocatalysis

Andreu, Rafael; Ferapontova, Elena LU ; Gorton, Lo LU and Calvente, Juan Jose (2007) In The Journal of Physical Chemistry Part B 111(2). p.469-477
Abstract
The study of direct electron transfer between enzymes and electrodes is frequently hampered by the small fraction of adsorbed proteins that remains electrochemically active. Here, we outline a strategy to overcome this limitation, which is based on a hierarchical analysis of steady-state electrocatalytic currents and the adoption of the "binary activity" hypothesis. The procedure is illustrated by studying the electrocatalytic response of horseradish peroxidase (HRP) adsorbed on graphite electrodes as a function of substrate (hydrogen peroxide) concentration, electrode potential, and solution pH. Individual contributions of the rates of substrate/enzyme reaction and of the electrode/enzyme electron exchange to the observed catalytic... (More)
The study of direct electron transfer between enzymes and electrodes is frequently hampered by the small fraction of adsorbed proteins that remains electrochemically active. Here, we outline a strategy to overcome this limitation, which is based on a hierarchical analysis of steady-state electrocatalytic currents and the adoption of the "binary activity" hypothesis. The procedure is illustrated by studying the electrocatalytic response of horseradish peroxidase (HRP) adsorbed on graphite electrodes as a function of substrate (hydrogen peroxide) concentration, electrode potential, and solution pH. Individual contributions of the rates of substrate/enzyme reaction and of the electrode/enzyme electron exchange to the observed catalytic currents were disentangled by taking advantage of their distinct dependence on substrate concentration and electrode potential. In the absence of nonturnover currents, adoption of the "binary activity" hypothesis provided values of the standard electron-transfer rate constant for reduction of HRP Compound II that are similar to those reported previously for reduction of cytochrome c peroxidase Compound II. The variation of the catalytic currents with applied potential was analyzed in terms of the non-adiabatic Marcus-DOS electron transfer theory. The availability of a broad potential window, where catalytic currents could be recorded, facilitates an accurate determination of both the reorganization energy and the maximum electron-transfer rate for HRP Compound II reduction. The variation of these two kinetic parameters with solution pH provides some indication of the nature and location of the acid/base groups that control the electronic exchange between enzyme and electrode. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
111
issue
2
pages
469 - 477
publisher
The American Chemical Society
external identifiers
  • wos:000243388800021
  • scopus:33847103553
ISSN
1520-5207
DOI
10.1021/jp064277i
language
English
LU publication?
yes
id
f0087095-c255-4e83-8237-20b87d244557 (old id 679304)
date added to LUP
2007-12-06 09:37:26
date last changed
2017-09-03 04:31:05
@article{f0087095-c255-4e83-8237-20b87d244557,
  abstract     = {The study of direct electron transfer between enzymes and electrodes is frequently hampered by the small fraction of adsorbed proteins that remains electrochemically active. Here, we outline a strategy to overcome this limitation, which is based on a hierarchical analysis of steady-state electrocatalytic currents and the adoption of the "binary activity" hypothesis. The procedure is illustrated by studying the electrocatalytic response of horseradish peroxidase (HRP) adsorbed on graphite electrodes as a function of substrate (hydrogen peroxide) concentration, electrode potential, and solution pH. Individual contributions of the rates of substrate/enzyme reaction and of the electrode/enzyme electron exchange to the observed catalytic currents were disentangled by taking advantage of their distinct dependence on substrate concentration and electrode potential. In the absence of nonturnover currents, adoption of the "binary activity" hypothesis provided values of the standard electron-transfer rate constant for reduction of HRP Compound II that are similar to those reported previously for reduction of cytochrome c peroxidase Compound II. The variation of the catalytic currents with applied potential was analyzed in terms of the non-adiabatic Marcus-DOS electron transfer theory. The availability of a broad potential window, where catalytic currents could be recorded, facilitates an accurate determination of both the reorganization energy and the maximum electron-transfer rate for HRP Compound II reduction. The variation of these two kinetic parameters with solution pH provides some indication of the nature and location of the acid/base groups that control the electronic exchange between enzyme and electrode.},
  author       = {Andreu, Rafael and Ferapontova, Elena and Gorton, Lo and Calvente, Juan Jose},
  issn         = {1520-5207},
  language     = {eng},
  number       = {2},
  pages        = {469--477},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Direct electron transfer kinetics in horseradish peroxidase electrocatalysis},
  url          = {http://dx.doi.org/10.1021/jp064277i},
  volume       = {111},
  year         = {2007},
}