ANTAGONISTIC EFFECTS OF ZINC AND ALUMINUM ON LEAD INHIBITION OF DELTA-AMINOLEVULINIC-ACID DEHYDRATASE

In vitro and in vivo studies regarding the influence of metals on δ-aminolevulinic acid dehydratase activity in erythrocytes indicate that a lead concentration of 4 μM/l completely inhibits the enzyme. Zinc activates the enzyme both in vitro and in vivo at concentrations greater than 76 μM/l. Aluminum has an inhibitory effect at all concentrations in vitro whereas it activates the enzyme in vivo. Zinc and aluminum together activate the enzyme in vivo. The in vitro activation of zinc is inhibited by increasing concentrations of aluminum. Aluminum and lead together depress the enzyme activity in an additive way that can be reactivated by the addition of zinc.