US EPA

4831028 

Journal Article 

Review 

Homeostatic impact of sulfite and hydrogen sulfide on cysteine catabolism 

Kohl, JB; Mellis, AT; Schwarz, G 

2018 

Yes 

British Journal of Pharmacology
ISSN: 0007-1188
EISSN: 1476-5381 

176 

4 

554-570 

English 

30088670 

10.1111/bph.14464 

WOS:000456799500005 

Cysteine is one of the two key sulfur-containing amino acids with important functions in, redox homeostasis, protein functionality and metabolism. Cysteine is taken up by mammals via the diet, and can also be derived from methionine via the transsulfuration pathway. The cellular concentration of cysteine is kept within a narrow range by controlling its synthesis and degradation. There are two pathways for the catabolism of cysteine leading to sulfate, taurine and thiosulfate as terminal products. The oxidative pathway produces taurine and sulfate, while the H2 S pathway involves different enzymatic reactions leading to the formation and clearance of H2 S, an important signalling molecule in mammals, resulting in thiosulfate and sulfate. Sulfite is a common intermediate in both catabolic pathways. Sulfite is considered as cytotoxic and produces neurotoxic S-sulfonates. As a result, a deficiency in in the terminal steps of cysteine or H2 S catabolism leads to severe forms of encephalopathy with accumulation of sulfite and H2 S in the body. This review links the homeostatic regulation of both cysteine catabolic pathways to sulfite and H2 S.