TQO plays a role in sulfur oxidation and is proposed to couple sulfur oxidation to dioxygen reduction; caldariellaquinone or sulfolobus quinone seem to serve to transfer electrons to the electron transport chain terminal oxidase formed by DoxBCE. 6-decylubiquinone + 2 thiosulfate = 6-decylubiquinol + tetrathionate Inhibited by sulfite, metabisulfite and dithonite. KM values measured using the TQO doxDA complex. Optimum pH is around 5, the pH range of activity varies in tested buffers. Increasing activity in the range between 20 and 92 degrees Celsius. Heterodimer of a large and a small subunit in a 2:2 stoichiometry (Probable). TQO may associate with the terminal oxidase formed by doxBCE. The thiosulfate dehydrogenase [quinone] subunits have originally been described as components of the aa3-type terminal oxidase.