Metal-ion catalysis in some reactions of hexacyanoferrate(III) ions. Part II. The oxidation of cysteine and related thiols in the presence of ethylenediaminetetra-acetic acid
Abstract
The rates and mechanism of the reaction of hexacyanoferrate(III) ions with cysteine. N-acetylcysteine, and 3-mer-captopropanoic acid have been examined in the presence of ethylenediaminetetra-acetic acid (EDTA). Copper catalysis, which is dominant in the absence of EDTA, persists, but with changes in behaviour which appear to reflect the change in the reduction potential of copper(II) and the differential lability of complexes of the II and I oxidation states. The results suggest that care is necessary if valid conclusions are to be drawn from experiments in which species like EDTA are used to eliminate reactions of metal cations.