On the mechanism of iodination of tyrosine

Existing data contain proof that the iodinating species of tyrosine and its derivatives contained in mixtures of iodine and iodide is hypoiodous acid, HOI. It appears likely that the peroxidase-catalyzed iodination reaction with hydrogen peroxide, tyrosine or a tyrosine derivative and either iodide or iodine as substrates involves enzyme-activated HOI.