Abstract: A metal-dendrimer complex in which the metal active site is deep within the three-dimensional dendrimer construct, has superoxide dismutase-like activity. In particular embodiments the complex is a copper(II)-dendrimer complex and the dendrimer construct is a dendritic polypeptide, and the copper(II) is complexed with imidazole groups provided by histidine side groups within the dendritic construct. The dendrimer construct has a generally globular shape, and the branched chains nearer the surface are sufficiently densely packed to restrict the movement of larger biomolecules into the dendritic construct toward the metal active sites. Smaller molecules such as the superoxide anion (O2·−) move freely from the milieu into the dendritic complex and to the metal active sites, where the dismutation of superoxide to hydrogen peroxide is effected; and smaller molecules such as hydrogen peroxide move freely out from the dendritic complex to the milieu.