Abstract
Sulfite ion (HSO3−) is one of the products when elemental sulfur is oxidized by the hydrogen sulfide:ferric ion oxidoreductase of Thiobacillus ferrooxidans AP19-3. Under the conditions in which HSO3− is accumulated in the cells, the iron oxidase of this bacterium was strongly inhibited by HSO3−. Since cytochrome c oxidase is one of the most important components of the iron oxidase enzyme system in T. ferrooxidans, effects of HSO3− on cytochrome c oxidase activity were studied with the plasma membranes of HSO3−-resistant and -sensitive strains of T. ferrooxidans, OK1-50 and AP19-3. The enzyme activity of AP19-3 compared with OK1-50 was strongly inhibited by HSO3−. To investigate the inhibition mechanism of HSO3− in T. ferrooxidans, cytochrome c oxidases were purified from both strains to an electrophoretically homogeneous state. Cytochrome c oxidase activity of a purified OK1-50 enzyme was not inhibited by 5 mM HSO3−. In contrast, the same concentration of HSO3− inhibited the enzyme activity of AP19-3 50%, indicating that the cytochrome c oxidase of OK1-50 was more resistant to HSO3− than that of AP19-3. Cytochrome c oxidases purified from both strains were composed of three subunits. However, the molecular weight of the largest subunit differed between OK1-50 and AP19-3. Apparent molecular weights of the three subunits of cytochrome c oxidases were 53,000, 24,000, and 19,000 for strain AP19-3 and 55,000, 24,000, and 19,000 for strain OK1-50, respectively.
Original language | English |
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Pages (from-to) | 1081-1086 |
Number of pages | 6 |
Journal | Bioscience, Biotechnology and Biochemistry |
Volume | 62 |
Issue number | 6 |
DOIs | |
Publication status | Published - Jan 1 1998 |
Keywords
- Bisulfite ion
- Cytochrome c oxidase
- Iron-oxidizing bacterium
- Resistance
- Thiobacillus ferrooxidans
ASJC Scopus subject areas
- Biotechnology
- Analytical Chemistry
- Biochemistry
- Applied Microbiology and Biotechnology
- Molecular Biology
- Organic Chemistry