A novel superoxide dismutase mimic based on copper (II) complex

Abstract

Superoxide dismutase (SOD) is an antioxidant enzyme involved in scavenging of superoxide and protects cells from oxidative damage. Unfortunately, natural enzyme can be easily denatured by environmental changes (such as temperature, pH and so on). Thus, tremendous efforts have been devoted to develop artificial SOD mimetics. In this study, copper (II)-cysteine complex (Cu-Cys) was synthesized and its SOD mimetic activity was investigated by pyrogallol autoxidation assay and electrochemical techniques. Pyrogallol autoxidation method was used for assaying SOD mimetic activity of Cu-Cys complex. Then, an application test for this novel SOD mimetic was performed by fabricating a novel biomimetic superoxide sensor based on electrochemical method. According to pyrogallol autoxidation method, Cu-Cys complex exhibited good SOD mimetic activity and followed a typical Michaelis-Menten behavior. The amperometric response of superoxide was monitored at a carbon paste electrode modified with Cu-Cys complex in potential 250 mV (vs. Ag/AgCl) and pH 7.4 phosphate buffer 0.1 M. The linear detection range and detection limit of superoxide at Cu-Cys complex modified carbon paste electrode were 11.3-316.4 and 5.3 μM respectively. The sensitivity of this superoxide sensor was 21.1 (nA/μM). Hydrogen peroxide, uric acid and citric acid showed no interference effect on the electrode performance. This remarkable performance indicates that Cu-Cys complex may be an efficient SOD mimetic candidate for constructing biomimetic superoxide sensor for clinical and/or industrial applications.