Copper-tripeptides (cuzymes) with peroxidase-mimetic activity

Abstract

Peroxidases are enzymes that use hydrogen peroxide to oxidize substrates such as 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ATBS). In this study, we showed that copper-tripeptide complexes ("cuzymes") also exhibited peroxidase-like activities. Different cuzymes could be formed by using various tripeptide ligands, such as GGG, GGH or HGG. However, the peroxidase-like activity of cuzymes depends on the sequence of the tripeptide (Cu-GGG > Cu-HGG > Cu-GGH). When ABTS was used as the substrate, the activity of Cu-GGG was 326 ± 1.5 U mg-1 which was 2.5 times higher than that of horseradish peroxidase (HRP). Copper-tripeptide complexes were also used to degrade trypan blue dye. By using 0.2 mM Cu-GGG and 0.2% H2O2, 200 ?M trypan blue could be degraded in 15 min at 50 °C. The degradation reaction followed second-order kinetics; the reaction rate was proportional to both H2O2 concentration and the copper-tripeptide concentration, but it was independent of the trypan blue concentration. Because copper-tripeptides catalyzed the oxidation reactions involving H2O2 effectively, they may have potential applications in biochemical assays and environmental remediation. This journal is © The Royal Society of Chemistry.