The ligands in the active centre of Cu-Zn superoxide dismutase was replaced with smaller and simpler ones, but still preserving the catalytically most important features of the original ones. The structure of the bare complex and that of the covalently grafted one was modeled by ab initio quantum chemical method. Tetrahedral geometric arrangement was found around the Cu(II) as well as the Zn(II) central ions. The ligands were loosely coupled allowing easy insertion of the incoming reactants.