Rhodanase

  Rhodanese is a Mitochondrion enzyme which detoxifies cyanide (CN^-) by converting it to thiocyanate (SCN^-).

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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 disulfide 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 decontamination cyanide, since the thiocyanate formed is relatively harmless. The use of thiosulfate solution as an antidote for cyanide poisoning is based on the activation of this enzymatic cycle.

References

• 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: 21054-21061.
• University of Minnesota (26 Dec 2007). "Fast-acting Cyanide Antidote Discovered". Press release. Retrieved on 1 Jan 2008.