Mechanism of Tetravalent Manganese Reduction with Elemental Sulfur by Thiobacillus ferrooxidans

Tsuyoshi Sugio, Yoshihiko Tsujita, Kouichi Hirayama, Kenji Inagaki, Tatsuo Tano

研究成果査読

14 被引用数 (Scopus)

抄録

Washed intact cells of iron-grown T. ferrooxidans API9-3 could reduce manganese dioxide (MnO2) enzymatically with elemental sulfur (S°) and the mechanism of Mn4+ reduction was studied. The optimum pH for Mn4+ reduction was 2.5. The amount of Mn4+ reduced by the strain was proportional to the amount of S° added to the reaction mixture. Anenzyme that directly catalyzes the reduction of Mn4+ to Mn2+ with S° was not found in the cell-free extract of this strain. T. ferrooxidans API9-3 was found to possess sulfur: ferric ion oxidoreductase (SFORase), which catalyzes the reduction of Fe3+ with S° to give Fe2+ and sulfite. The reduction of Mn4+ was inhibited by a specific inhibitor of SFORase or diamide, strongly suggesting that SFORase is involved in the Mn4+ reduction in this strain. The involvement of SFORase in Mn4+ reduction was further supported by the following results. Both the amounts of Fe2+ and sulflte produced by SFORase were markedly reduced by MnO2. The amount of Mn4+ reduced increased 5.4-fold with 1 mm ferric ion and 10-fold with 2.5 mm cyanide or an inhibitor of iron oxidase, respectively. The sulfite and Fe2+ were chemically oxidized by MnO2 instantly. From the results, it is concluded that the Mn4+ reduction with S° in this strain occurs through two steps. In the first step S° is enzymatically oxidized by SFORase to give Fe2+ and sulfite, and in the second step these two reduced compounds are chemically reduced by MnO2 to give Mn2+.

本文言語English
ページ(範囲)185-190
ページ数6
ジャーナルAgricultural and Biological Chemistry
52
1
DOI
出版ステータスPublished - 1988

ASJC Scopus subject areas

  • 生化学、遺伝学、分子生物学一般
  • 農業および生物科学一般

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