Biochemical studies of a soxF-encoded monomeric flavoprotein purified from the green sulfur bacterium Chlorobaculum tepidum that stimulates in vitro thiosulfate oxidation.

In the green sulfur bacterium Chlorobaculum tepidum, three sulfur oxidizing enzyme system (Sox) proteins, SoxAXK, SoxYZ, and SoxB (the core TOMES, thiosulfate oxidizing multi-enzyme system) are essential to in vitro thiosulfate oxidation. We purified monomeric flavoprotein SoxF from this bacterium, which had sulfide dehydrogenase activity. SoxF enhanced the thiosulfate oxidation activity of the purified core TOMES with various cytochromes as electron acceptors to different degrees without any change in the affinity for thiosulfate.

SoxAX binding protein, a novel component of the thiosulfate-oxidizing multienzyme system in the green sulfur bacterium Chlorobium tepidum.

From the photosynthetic green sulfur bacterium Chlorobium tepidum (pro synon. Chlorobaculum tepidum), we have purified three factors indispensable for the thiosulfate-dependent reduction of the small, monoheme cytochrome c(554). These are homologues of sulfur-oxidizing (Sox) system factors found in various thiosulfate-oxidizing bacteria.