Isolation and preliminary characterization of a respiratory nitrate reductase from hydrocarbon-degrading bacterium <Emphasis Type="Italic">Gordonia alkanivorans</Emphasis> S7 |
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Authors: | Irena Romanowska Ewa Kwapisz Magdalena Mitka Stanis?aw Bielecki |
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Institution: | (1) Department of Biotechnology and Food Sciences, Institute of Technical Biochemistry, Technical University of Lodz, Stefanowskiego 4/10, 90-924 Lodz, Poland |
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Abstract: | Gordonia alkanivorans S7 is an efficient degrader of fuel oil hydrocarbons that can simultaneously utilize oxygen and nitrate as electron acceptors.
The respiratory nitrate reductase (Nar) from this organism has been isolated using ion exchange chromatography and gel filtration,
and then preliminarily characterized. PAGE, SDS-PAGE and gel filtration chromatography revealed that Nar consisted of three
subunits of 103, 53 and 25 kDa. The enzyme was optimally active at pH 7.9 and 40°C. K
m values for NO3
− (110 μM) and for ClO3
− (138 μM) were determined for a reduced viologen as an electron donor. The purified Nar did not use NADH as the electron donor
to reduce nitrate or chlorate. Azide was a strong inhibitor of its activity. Our results imply that enzyme isolated from G. alkanivorans S7 is a respiratory membrane-bound nitrate reductase. This is the first report of purification of a nitrate reductase from
Gordonia species. |
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Keywords: | |
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