The Mechanism of the Copper Ion Catalyzed Autoxidation of Cysteine in Alkaline Medium

Abstract

Quantitative e.s.r. measurements carried out during the copper catalysed alkaline autoxidation of cysteine show that the Cu(II)-dicysteine complex represents almost the total amount of copper. Only a small fraction (<2%) of the copper ions might be present in a state which is not detectable by e.s.r.The kinetics of the catalytic reaction obeys the rate expression The results cannot be explained by a simple Cu(II)/Cu(I) redox mechanism.Instead, a reaction model is proposed, which is based upon the involvement of a thiyl- and a superoxo-activated Cu(II) complex, respectively. These two types of complexes are operative in a chainlike propagation cycle.