TY - JOUR
T1 - Adsorptive immobilization of cytochrome c on indium/tin oxide (ITO)
T2 - Electrochemical evidence for electron transfer-induced conformational changes
AU - El Kasmi, Asma
AU - Leopold, Michael C.
AU - Galligan, Ryan
AU - Robertson, Rebecca T.
AU - Saavedra, S. Scott
AU - El Kacemi, Kacem
AU - Bowden, Edmond F.
N1 - Funding Information:
We acknowledge the Moroccan–American Commission for Educational and Cultural Exchange for providing a Fulbright grant to Dr. A. El Kasmi to support her stays at NCSU. This work was supported in part by grants from the US National Science Foundation to E.F.B (CHE9816268) and S.S.S. (CHE9726132 and CHE0108805) and from the US National Institutes of Health to S.S.S. (R21GM59242).
PY - 2002
Y1 - 2002
N2 - The adsorptive immobilization and electrochemistry of horse and yeast cytochrome c on indium/tin oxide (ITO) electrodes is reported. Near-monolayer coverage was achieved in pH 7 phosphate buffers of ionic strength equal to 10 and 50 mM, respectively, for the horse and yeast species. The layers exhibit very well-behaved voltammetry and are stable on the timescale of hours to days. Cyclic voltammetry revealed quasireversible behavior that is a product of both electron transfer (ET) kinetics and ET-induced conformational changes. A square scheme mechanism linking the redox states and the conformational states is proposed. Using a simple ET kinetic model that adequately describes the voltammetry at higher scan rates, a standard ET rate constant of 18 s-1 was determined for adsorbed horse cytochrome c. With decreasing scan rate, we observed a limiting peak separation of approximately 10 mV, an example of unusual quasireversibility (UQR) that we attribute to the effect of conformational changes. Finally we note that the intrinsic cytochrome c ET rate on ITO is some 6 orders of magnitude less than for gold.
AB - The adsorptive immobilization and electrochemistry of horse and yeast cytochrome c on indium/tin oxide (ITO) electrodes is reported. Near-monolayer coverage was achieved in pH 7 phosphate buffers of ionic strength equal to 10 and 50 mM, respectively, for the horse and yeast species. The layers exhibit very well-behaved voltammetry and are stable on the timescale of hours to days. Cyclic voltammetry revealed quasireversible behavior that is a product of both electron transfer (ET) kinetics and ET-induced conformational changes. A square scheme mechanism linking the redox states and the conformational states is proposed. Using a simple ET kinetic model that adequately describes the voltammetry at higher scan rates, a standard ET rate constant of 18 s-1 was determined for adsorbed horse cytochrome c. With decreasing scan rate, we observed a limiting peak separation of approximately 10 mV, an example of unusual quasireversibility (UQR) that we attribute to the effect of conformational changes. Finally we note that the intrinsic cytochrome c ET rate on ITO is some 6 orders of magnitude less than for gold.
KW - Cytochrome c monolayers
KW - Indium/tin oxide
KW - Interfacial electron transfer kinetics
KW - Redox-linked conformational changes
KW - Unusual quasireversibility
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U2 - 10.1016/S1388-2481(01)00299-5
DO - 10.1016/S1388-2481(01)00299-5
M3 - Article
AN - SCOPUS:0036175151
SN - 1388-2481
VL - 4
SP - 177
EP - 181
JO - Electrochemistry Communications
JF - Electrochemistry Communications
IS - 2
ER -