Thiosulfate-cleaving enzyme

The enzyme catalyzing the reaction (4.4) is usually called rhodanese and is thought to occur widely in various organisms. However, as rhodanese requires cyanide of fairly high concentrations (ca. 1 mM) which are not present in normal organisms, the enzyme seems not to occur in Nature. But enzymes occur which have rhodanese activity, e.g., the thiosulfate-cleaving enzyme shows rhodanese activity. Namely, the term rhodanese should not be used as the name of an enzyme, but its use should be limited to the enzymatic activity. 

Thus, the thiosulfate-cleaving enzyme does not show rhodanese activity in the presence of the sulfur-accepting protein (Fukumori et al., 1989). 

The critical step in the use of multiple sulfur linkages is the availability of HS" from the reduced enzyme system. The HS" could possibly attack the cyclic or the acyclic multiple sulfur linkages through a nucleophilic mechanism. The cleaved sulfide linkages undergo oxidation to sulfite or thiosulfate. This seems a plausible pathway for the oxidation of the sulfur compounds in the present study. 

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