Effects of aluminium, lead and zinc on delta-aminolaevulinic acid dehydratase

The effects of aluminium, lead and zinc on ALA dehydratase were examined in vitro and in vivo. Aluminium alone added to the erythrocyte enzyme assay caused a highly significant increase in enzyme activity. A similar result was found with zinc alone. When lead and aluminium were added together, the inhibition found with lead alone was depressed in an additive manner by aluminium. Zinc and aluminium together showed an activation that was stoichiometrically additive. Studies in vivo using rats injected with aluminium and lead showed similar results for hepatic ALA dehydratase as those found in vitro.