Destroys radicals which are normally produced within the cells and which are toxic to biological systems. 2 H(+) + 2 superoxide = H2O2 + O2 Binds 1 copper ion per subunit. Binds 1 zinc ion per subunit. Homodimer in holo form. In apo form, heterodimer with CCS1. Zinc-binding at 'His-16' of CCS1 and Glu-43 of apo-SOD1 is required for this heterodimerization. A small percentage (around 1-5 percent) localizes to the mitochondrial intermembrane space. Present with 519000 molecules/cell in log phase SD medium. Belongs to the Cu-Zn superoxide dismutase family.