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Publication 566
J. Electroanal.
Chem., 549, 61-70, 2003
DOI: 10.1016/S0022-0728(03)00285-7 |
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Cyclic voltammetry of immobilized redox enzymes. Interference
of steady-state and non-steady-state Michaelis–Menten
kinetics of the enzyme–redox cosubstrate system
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Benoit
Limoges and Jean-Michel Savéant
Contribution from the Laboratoire d'Electrochimie
Moléculaire, Université de Paris 7 -
Denis Diderot, Case Courrier 7107, 2 place Jussieu,
75251 Paris Cedex 05, France.
The catalytic response of an immobilized redox enzyme connected to the
electrode by a freely diffusing mediator (cosubstrate) may depend of
the Michaelis–Menten characteristics of the enzyme–redox
cosubstrate system. How the electrochemical responses are related then
to the corresponding rate constants, to the amount of enzyme on the electrode,
to the concentration and to the mass transport parameters is analyzed
in the framework of cyclic voltammetry, for the purpose of establishing
diagnostic criteria and procedures for rate constant determination based
on the shape, height and potential location of the catalytic responses.
Two main kinetic regimes are discussed. The first one concerns systems
in which the two enzyme forms are under steady-state conditions. The
maximal effect of Michaelis–Menten kinetics is expected when the
decomposition of the enzyme–cosubstrate complex is the rate-determining
step. This case is analyzed in detail after removal of the steady-state
condition. Although the derivation of diagnostic criteria and closed
form expressions of the cyclic voltammetric responses is privileged,
numerical simulation procedures are described that are applicable to
the systems under discussion, but also, with little adaptation, to any
other immobilized redox enzyme systems. |
