Cytoglobin has potent superoxide dismutase function
Jay L. Zweíer, Craig Hemann, Tapan Kumar Kundu, Mohamed G. Ewees, Sahar A. Khaleel, Alexandre Samouilov, Govindasamy Ilangovan, Mohamed A. El‐Mahdy
Abstract
Significance We identified a novel function of cytoglobin (Cygb) as an efficient superoxide dismutase (SOD) with a high–bimolecular dismutation rate on the order of 10 8 M −1 ⋅ s −1 . It is the first Fe-centered SOD identified in mammalian cells and the only member of the globin family shown to have potent SOD activity. This SOD function of Cygb may serve to explain the prior reports of its antioxidative activity and the toxicities and disease seen with its genetic deletion, including the increased incidence of tumors. Combined with its potent NO dioxygenase activity, Cygb would be highly effective in decreasing both O 2 •− and NO levels, serving to decrease the formation of peroxynitrite and secondary oxidative injury.