Thiosulfate reductase (TSR)

Thiosulfate reductase is a microbial enzyme, primarily identified in anaerobic and facultative anaerobic bacteria such as Salmonella enterica and Desulfovibrio species, that catalyzes the reduction of thiosulfate to sulfite and hydrogen sulfide (H2S) (UniProt: P0A8Q3). This enzyme plays a critical role in bacterial anaerobic respiration, allowing these organisms to thrive in the low-oxygen environment of the human gut (NCBI: EC 1.8.5.5). While not a human protein, it is considered a significant therapeutic target because excessive H2S production by the gut microbiota is linked to the disruption of the colonic mucosal barrier and the inhibition of butyrate oxidation, which are key factors in the development of ulcerative colitis and colorectal cancer (PubMed: 25211151). Pharmacological targeting of thiosulfate reductase involves the use of bismuth-based compounds that serve both as enzymatic inhibitors and H2S scavengers to reduce gut toxicity and inflammation (PubMed: 31086111). Monitoring the levels of thiosulfate-reducing bacteria and their metabolic byproducts serves as a biomarker for disease severity and therapeutic response in patients with chronic inflammatory bowel conditions.

Other names

Thiosulfate reductase (thiol-dependent)Thiosulfate reductase (cytochrome-dependent)phsAThiosulfate:ferredoxin oxidoreductaseThiosulfate sulfurtransferase

Inhibition of bacterial sulfur metabolism and enzymatic hydrogen sulfide production; sequestration of hydrogen sulfide through the formation of insoluble metal sulfides.