Superoxide dismutase activity of a Cu–Zn complex—bare and immobilised

Abstract

A binuclear, imidazolato-bridged complex (Cu(II)-diethylenetriamino-μ-imidazolato-Zn(II)-tris(aminoethyl)amine perchlorate) was prepared and immobilised on silica gel or among the layers of montmorillonite. Immobilisation occurred via hydrogen bonding for the silica gel and through electrostatic forces for the montmorillonite. The obtained substances were characterised by EPR and FT-IR spectroscopies and their thermal behaviour was studied by thermogravimetry. The superoxide dismutase (SOD) activity of the complex before and after immobilisation was studied by a SOD assay. It was found that the SOD activity of the host-free complex increased by more than an order of magnitude and approached the efficiency of the real enzyme when silica gel was used as host. The enhanced activity could be assigned to the formation of magnetically isolated centers in the silica pores. On the other hand, the immobilisation with montmorillonite slightly reduced the SOD activity.