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Journal of Bacteriology, April 2007, p. 3312-3317, Vol. 189, No. 8
0021-9193/07/$08.00+0     doi:10.1128/JB.01525-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Characterization of an Exceedingly Active NADH Oxidase from the Anaerobic Hyperthermophilic Bacterium Thermotoga maritima{triangledown}

Xianqin Yang and Kesen Ma*

Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada

Received 29 September 2006/ Accepted 31 January 2007

An NADH oxidase from the anaerobic hyperthermophilic bacterium Thermotoga maritima was purified. The enzyme was very active in catalyzing the reduction of oxygen to hydrogen peroxide with an optimal pH value of 7 at 80°C. The Vmax was 230 ± 14 µmol/min/mg (kcat/Km = 548,000 min–1 mM–1), and the Km values for NADH and oxygen were 42 ± 3 and 43 ± 4 µM, respectively. The NADH oxidase was a heterodimeric flavoprotein with two subunits with molecular masses of 54 kDa and 46 kDa. Its gene sequences were identified, and the enzyme might represent a new type of NADH oxidase in anaerobes. An NADH-dependent peroxidase with a specific activity of 0.1 U/mg was also present in the cell extract of T. maritima.

* Corresponding author. Mailing address: Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada. Phone: (519) 888-4567, ext. 33562. Fax: (519) 746-0614. E-mail: kma{at}uwaterloo.ca

{triangledown} Published ahead of print on 9 February 2007.

Journal of Bacteriology, April 2007, p. 3312-3317, Vol. 189, No. 8
0021-9193/07/$08.00+0     doi:10.1128/JB.01525-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.





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