Direct Electrochemistry of a Bacterial Sulfite Dehydrogenase
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- 作者：Kondo-Franç ; ois Aguey-Zinsou ; Paul V. Bernhardt ; Ulrike Kappler ; and Alastair G. McEwan
- 刊名：Journal of the American Chemical Society
- 出版年：2003
- 出版时间：January 15, 2003
- 年：2003
- 卷：125
- 期：2
- 页码：530 - 535
- 全文大小：106K
- 年卷期：v.125,no.2(January 15, 2003)
- ISSN：1520-5126
文摘
Sulfite dehydrogenase from Starkeya novella is an 
heterodimer comprising a 40.6 kDa subunit(containing the Mo cofactor) and a smaller 8.8 kDa heme c subunit. The enzyme catalyses the oxidationof sulfite to sulfate with the natural electron acceptor being cytochrome c550. Its catalytic mechanism isthought to resemble that found in eukaryotic sulfite oxidases. Using protein film voltammetry and redoxpotentiometry, we have identified both Mo- and heme-centered redox responses from the enzymeimmobilized on a pyrolytic graphite working electrode: Em,8 (FeIII/II) +177 mV; Em,8 (MoVI/V) +211 mV andEm,8 (MoV/IV) -118 mV vs NHE; Upon addition of sulfite to the electrochemical cell a steady-statevoltammogram is observed and an apparent Michaelis constant (Km) of 26(1) 
M was determined for theenzyme immobilized on the working electrode surface, which is comparable with the value obtained fromsolution assays.
heterodimer comprising a 40.6 kDa subunit(containing the Mo cofactor) and a smaller 8.8 kDa heme c subunit. The enzyme catalyses the oxidationof sulfite to sulfate with the natural electron acceptor being cytochrome c550. Its catalytic mechanism isthought to resemble that found in eukaryotic sulfite oxidases. Using protein film voltammetry and redoxpotentiometry, we have identified both Mo- and heme-centered redox responses from the enzymeimmobilized on a pyrolytic graphite working electrode: Em,8 (FeIII/II) +177 mV; Em,8 (MoVI/V) +211 mV andEm,8 (MoV/IV) -118 mV vs NHE; Upon addition of sulfite to the electrochemical cell a steady-statevoltammogram is observed and an apparent Michaelis constant (Km) of 26(1) M was determined for theenzyme immobilized on the working electrode surface, which is comparable with the value obtained fromsolution assays.