Purification and characterization of a sulfite:cytochrome c oxidoreductase from Thiobacillus acidophilus |
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| Affiliation: | 1. Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, P.O. Box 353, Beijing, 100190, PR China;2. State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, PR China;3. University of Chinese Academy of Sciences, Beijing, 100049, PR China;1. Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30239 Krakow, Poland;2. Faculty of Chemistry, Jagiellonian University, Ingardena 3, Krakow 30060, Poland;3. Faculty of Agriculture and Economics, University of Agriculture in Krakow, Mickiewicza 21, 31120 Krakow, Poland;4. Molecular and Environmental Sciences Group, Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada;5. Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA;1. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China;2. Anhui Institute of Geo-Environment Monitoring, Hefei 230009, China;1. State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, Heilongjiang Province 150090, China;2. Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan;3. Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China |
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| Abstract: | Cell-free extracts of Thiobacillus acidophilus prepared at neutral pH showed oxidation of sulfite to sulfate with ferricyanide as electron acceptor. Horse heart cytochrome c could be used as alternative electron acceptor; however, the observed activity was only 0.1% of that found for ferricyanide. The enzyme responsible for the oxidation of sulfite was purified to homogeneity. The purified enzyme was a monomer of 42 kDa and contained one haem c per monomer. Electron paramagnetic resonance (EPR) spectroscopical analysis of the sulfite:cytochrome c oxidoreductase showed the presence of molybdenum (V), only after reduction of the enzyme with sulfite. The pH optimum for the enzymatic reaction was 7.5 and the temperature optimum 40°C. Enzymatic activity was strongly reduced in the presence of the anions: chloride, phosphate and nitrate. In contrast to other enzymes involved in sulfur metabolism and previously isolated from T. acidophilus, sulfite:cytochrome c oxidoreductase activity is not stimulated by the presence of sulfate ions. |
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