Inhibition of both peroxidase and laccase by desferal (desferrioxamine mesylate)

The effect of desferal (desferrioxamine mesylate), a transition metal chelator with a stability constant for iron of 10(31), On th, catalytic activity of the hemoprotein peroxidase, and on the catalytic activities of the cuproproteins, laccase and catechol oxidase, was studied. The results showed that desferal is an inhibitor of peroxidase and laccase activities but not of catechol oxidase activity, the inhibitory properties being strongly dependent on the phenolic substrate used to measure enzymatic activities. Thus, the inhibitory effect of desferal was not dependent on the nature of the prosthetic group. However, its use as an inhibitor of phenol-oxidizing enzymes, such as peroxidase and laccase, is promising since desferal seems to deactivate phenoxy radicals formed by the action of these enzymes. A mechanism to explain the inhibitory effect of desferal on these phenol-oxidizing enzymes, based on the reaction of desferal with phenoxy radicals, is proposed.