EC=1.15.1.1

Superoxide dismutase (SOD) is a 152aa enzyme previously known as haemocuprein or erythrocuprein and belongs to the Cu-Zn superoxide dismutase family. In mammals, it was first described in bovine erythrocytes and is a homodimeric non-covalently bound protein where each monomer has one intrachain disulphide and one free sulfhydryl, and two Cu+2 atoms and two Zn+2 atoms. SOD catalyzes the dismutation of superoxide radicals to hydrogen peroxide and molecular oxygen and thus plays an important role in the defense of cells against the toxic effects of oxygen radicals. It competes with nitric oxide (NO) for superoxide anion, thus promoting the activity of NO. SOD may also play a critical role in suppressing apoptosis in cultured rat ovarian follicles, neural cell lines, and transgenic mice by preventing the conversion of NO to peroxynitrite.