The design of metalloproteins allows us to better understand metal complexation in proteins and the resulting function. In this study, we incorporated a Cu^(2+)-binding site into a natural protein domain, the 58 amino acid c-Crk-SH3, to create a miniaturized superoxide dismutase model, termed SO1. The resulting low complexity metalloprotein was characterized for structure and function by circular dichroism and UV spectroscopy as well as EPR spectroscopy and X-ray crystallography. The …