A high-potential nonheme iron protein (HiPIP)-linked,thiosulfate-oxidizing enzyme derived fromChromatium vinosum

A thiosulfate-oxidizing enzyme was partially purified fromChromatium vinosum, and some of its properties were studied. The enzyme rapidly reducede HiPIP (high-potential nonheme iron protein) in the presence of thiosulfate. Cytochromesc of yeast and tuna and ferricyanide also acted well as electron acceptors for the enzyme; horse cytochromec was a poor electron acceptor. Cytochromec-552, cytochromec′, and cytochromec-553 did not act as electron acceptors. The enzyme was inhibited by cyanide and sulfite. On the basis of the stoichiometry in reduction of ferricyanide catalyzed by the enzyme in the presence of thiosulfate, the oxidized product of thiosulfate was inferred to be tetrathionate.