Iron (III) reduction: A novel activity of the human NAD(P)H:oxidoreductase
Journal Article
·
· Biochemical and Biophysical Research Communications
- Department of Microbiology, University of Georgia, 1000 Cedar Street, Athens, GA 30602-2605 (United States)
NAD(P)H:quinone oxidoreductase (NQO1; EC 1.6.99.2) catalyzes a two-electron transfer involved in the protection of cells from reactive oxygen species. These reactive oxygen species are often generated by the one-electron reduction of quinones or quinone analogs. We report here on the previously unreported Fe(III) reduction activity of human NQO1. Under steady state conditions with Fe(III) citrate, the apparent Michaelis-Menten constant (K{sub m}{sup app}) was {approx}0.3nM and the apparent maximum velocity (V{sub max}{sup app}) was 16Umg{sup -1}. Substrate inhibition was observed above 5nM. NADH was the electron donor, K{sub m}{sup app}=340{mu}M and V{sub max}{sup app}=46Umg{sup -1}. FAD was also a cofactor with a K{sub m}{sup app} of 3.1{mu}M and V{sub max}{sup app} of 89Umg{sup -1}. The turnover number for NADH oxidation was 25s{sup -1}. Possible physiological roles of the Fe(III) reduction by this enzyme are discussed.
- OSTI ID:
- 20979787
- Journal Information:
- Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 2 Vol. 353; ISSN BBRCA9; ISSN 0006-291X
- Country of Publication:
- United States
- Language:
- English
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