Abstract
The superoxide dismutase which is present in the cytosol of eukaryotic cells is a cuprozinc enzyme (SODCu2Zn2)(E.C. 1. 15. 1. 1). It catalyses the dismutation of superoxide anions O2 to hydrogen peroxide (H2O2) plus oxygen. the importance of copper for the activity of the enzyme is well established and this activity can be used as a marker of copper status. Zinc is also essential for many enzymatic activities: however, the link between zinc nutritional status and SOD activity remains poorly explored. the aim of the present work was to discover whether there is a relationship in vivo between catalytic activity of superoxide dismutase and nutritional status of zinc. Three ap proaches have been used; the eflect of increasing concentrations of zinc on the in vitro activity of different forms of the enzyme: native SOD, zinc-depleted (SODCu2E2)and zinc- and copper-depleted apoenzyme (SODE2E2)The importance of zinc on SOD activity in vivo was also studied by determining the SOD activity in zinc-deficient rats, and in dialysis patients in whom it is known that the trace element status is highly disturbed. Our data confirm that zinc modulates superoxide dismutase activity in vitro, since the addition of zinc to SODCu2E2led a significant increase in catalytic activity. Moreover, in vivo SOD activity in zinc-deficient rats was decreased compared with control, and chronic renal patients, showed a concommitant decrease in SOD activity which paralleled their zinc levels.