The interaction between superoxide dismutase and doxorubicin. An electron spin resonance approach

Abstract

The interaction between copper–zinc superoxide dismutase (Cu–Zn SOD) and anthracycline antitumour drugs (doxorubicin and 4′-epidoxorubicin) has been investigated by e.s.r. spectroscopy. The Cu²⁺ centres within the enzyme structure are available for anthracycline coordination in a way similar to that observed for copper-anthracycline derivatives when CuCl₂ was used and at high r values (where r is the anthracycline/Cu²⁺ molar ratio). The amount of copper extracted by the drug increases as the protein concentration decreases, and several stacked anthracycline units are found to bind to one Cu²⁺ centre.