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, catalyti c activity of the hemoprotein peroxidase, and on the catalytic activit ies of the cuproproteins, laccase and catechol oxidase, was studied. T he results showed that desferal is an inhibitor of peroxidase and lacc ase activities but not of catechol oxidase activity, the inhibitory pr operties being strongly dependent on the phenolic substrate used to me asure enzymatic activities. Thus, the inhibitory effect of desferal wa s not dependent on the nature of the prosthetic group. However, its us e as an inhibitor of phenol-oxidizing enzymes, such as peroxidase and laccase, is promising since desferal seems to deactivate phenoxy radic als 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.