5.A.3.5.1
Thiosulfate reductase, PhsABC (Heinzinger et al., 1995) (Clark and Barrett 1987). Menaquinone is the sole electron donor. The endoergonic reduction reaction is driven by the pmf by a reverse loop mechanism (Stoffels et al. 2012). The enzyme can catalyze oxidation of sulfide to sulfite and sulfite to thiosulfate in an exergonic reaction that is pmf-independent (Stoffels et al. 2012). Because the endoergonic reaction is dependent on the pmf, there may be a proton channels in the complex, (possibly subunit C) that allows proton flux into the cell, coupled to the reduction reaction.