This reaction takes place in two steps. The diagram on the right shows the crystallographically-determined structure of rhodanese. In the first step, thiosulfate reacts with the thiol group on cysteine-247 1, to form a persulfide 2. In the second step, the disulfide reacts with cyanide to produce thiocyanate, itself being converted back into the "normal" thiol 1.
This reaction is important for the treatment of exposure to cyanide, since the thiocyanate formed is less toxic.[medical citation needed] The use of thiosulfate solution as an antidote for cyanide poisoning is based on the activation of this enzymatic cycle.
Rhodanese shares evolutionary relationship with a large family of proteins, including
- Cdc25 phosphatase catalytic domain.
- non-catalytic domains of eukaryotic dual-specificity MAPK-phosphatases
- non-catalytic domains of yeast PTP-type MAPK-phosphatases
- non-catalytic domains of yeast Ubp4, Ubp5, Ubp7
- non-catalytic domains of mammalian Ubp-Y
- Drosophila heat shock protein HSP-67BB
- several bacterial cold-shock and phage shock proteins
- plant senescence associated proteins
- catalytic and non-catalytic domains of rhodanese (see <db_xref db="INTERPRO" dbkey="IPR001307" />).
Rhodanese has an internal duplication. This domain is found as a single copy in other proteins, including phosphatases and ubiquitin C-terminal hydrolases.
Human proteins containing this domain
- Cipollone R, Ascenzi P, Tomao P, Imperi F, Visca P (2008). "Enzymatic detoxification of cyanide: clues from Pseudomonas aeruginosa Rhodanese". J. Mol. Microbiol. Biotechnol. 15 (2-3): 199–211. doi:10.1159/000121331. PMID 18685272.
- Gliubich F, Gazerro M, Zanotti G, Delbono S, Bombieri G, Berni R (1996). "Active site structural features for chemically modified forms of rhodanese". J. Biol. Chem. 271 (35): 21054–21061. doi:10.1074/jbc.271.35.21054. PMID 8702871.
- F. Gliubich, M. Gazerro, G. Zanotti, S. Delbono, G. Bombieri, R. Berni (1996). "Active Site Structural Features for Chemically Modified Forms of Rhodanese". Journal of Biological Chemistry 271 (35): 21054–21061. doi:10.1074/jbc.271.35.21054. PMID 8702871.