Thiosulphate:quinone oxidoreductase (TQO) is one of the early steps in elemental sulphur oxidation. A novel TQO enzyme was purified from the thermo-acidophilic archaeon Acidianus ambivalens and shown to consist of a large subunit (DoxD) and a smaller subunit (DoxA). The DoxD- and DoxA-like two subunits are fused together in a single polypeptide in Swiss:Q8AAF0.

1: Coupling of the pathway of sulphur oxidation to dioxygen reduction: characterization of a novel membrane-bound thiosulphate:quinone oxidoreductase. Muller FH, Bandeiras TM, Urich T, Teixeira M, Gomes CM, Kletzin A; Mol Microbiol. 2004;53:1147-1160. PMID:15306018