Publication
577
J. Electroanal.
Chem., 562 (1), 43-52, 2004
DOI: 10.1016/j.jelechem.2003.07.035 |
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Catalysis by immobilized redox enzymes. Diagnosis of inactivation
and reactivation effects through odd cyclic voltammetric
responses
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Benoit
Limoges and Jean-Michel Savéant
Laboratoire d'Electrochimie Moléculaire,
Université de Paris 7 - Denis Diderot, Case
Courrier 7107, 2 place Jussieu, 75251 Paris Cedex
05, France
Odd cyclic voltammetric responses, with an inverted peak appearing on
the reverse scan, have been recently reported for the catalysis of immobilized
enzymes involved in a direct electron transfer at the electrode surface
and implicated in a chemical inactivation/redox reactivation mechanism.
In this work, it is shown that this twisted reverse trace behavior can
be related rigorously and quantitatively to such a reaction scheme by
means of a minimal number of dimensionless parameters. As a prelude,
the requirements for ‘pure catalytic’ conditions to be achieved
are established quantitatively. It is also shown that simple irreversible
or reversible inactivation does not entail the appearance of twisted
reverse traces. The quantitative analysis of the inactivation/reactivation
mechanism does not lead to a closed form expression of the current responses,
but rather requires the numerical resolution of the pertinent differential
equations. This approach may be readily extended to virtually any kind
of mechanism, including more complex reactions schemes, distance-dependent
electron transfer kinetics, the use of immobilized or free-moving redox
cosubstrates, consideration of substrate mass transport limitations,
etc. |
