These proteins appear to have some sequence similarity with Pfam:PF04173 but their function is unknown [1].

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