The reaction mechanism of nitrosothiols with copper(I)

Copper and other transition metal ions and their complexes are catalysts for the decomposition of nitrosothiols. In this way they catalyze the biological functions of nitrosothiols. The kinetics and mechanism of the reaction of two nitrosothiols, S-nitrosothiolactic acid and S-nitrosoglutathione (GSNO), with copper(I) are reported. The kinetics of the reaction of Cu(MeCN)+(n) (n=0-3) with the nitrosothiols were studied. The results indicate that Cu+(aq) is the active species in the GSNO system, with k(Cu+(aq)+GSNO)=(9.4 +/- 2.0) x 10(7) dm3 mol(-1) s(-1). The results also indicate that the Cu(MeCN)+(n) (n=0-3) complexes react with S-nitrosothiolactic acid. Transient species are formed in these processes. The results suggest that these species contain copper(I) and thiol. The results shed light on the catalytic role of copper complexes in the decomposition of S-nitrosothiols.