Thiosulphate oxidation and cytochromes in Thiobacillus X. 2. Thiosulphate-oxidizing enzyme

Abstract

Some properties of the thiosulphate-oxidizing enzyme from the aerobic sulphur autotroph Thiobacillus X are described. The enzyme catalyzes the oxidation of thiosulphate to tetrathionate with ferricyanide or Thiobacillus X cytochrome 553.5 as electron acceptors. Other soluble cytochromes from the same bacterium do not react directly with thiosulphate-oxidizing enzyme but become reduced in the presence of thiosulphate, enzyme and cytochrome 553.5. A particulate preparation from Thiobacillus X oxidizes the reduced soluble cytochromes 550 (1), 553.5, 557 (1) and the components of the acidic fraction. In the presence of cytochrome 553.5 and thiosulphate-oxidizing enzyme, the particles oxidize thiosulphate to tetrathionate with the consumption of oxygen.