Abstract
When phenylalanine was treated with the ascorbic acid-hydrogen peroxide system in acetate buffer (pH 4.0), o-tyrosine, m-tyrosine and p-tyrosine were identified as hydroxylated products. The hydroxylation of phenylalanine in the ascorbic acid-hydrogen peroxide system was prevented by radical scavengers, e.g., potassium iodide, potassium bromide, sodium thiocyanate, sodium formate, mannose, ethyl alcohol, superoxide dismutase and Tiron. The possibility is discussed that the active species responsible for the hydroxylation of phenylalanine in the ascorbic acid-hydrogen peroxide system is the hydroxyl radical.
