A comparative study of the end-products of uric acid oxidation by peroxidases.

Uric acid has long been considered to be a metabolically inert endproduct of purine metabolism in the human (1, 2). This view has been challenged by Folin, Berglund, and Derick (3), who, in an extensive review of the subject, reported that only about 50 per cent of intravenously administered uric acid in man could be recovered. More recently, with the use of Nls-labeled uric acid, Benedict, Forsham, and Stetten (4) calculated that only 70 to 80 per cent of the uric acid formed each day by normal humans could be isolated in the urine. In more recent experiments, Wyngaarden and Stetten (5) have shown that, after administering 1000 mg. of uric acid-l ,3-NlS to a normal human, 17 per cent of the administered N15 could be recovered as urinary urea and 1 per cent as urinary ammonia, thus establishing uricolysis in the human. These may be considered to be low values, since they do not take into consideration the initially high elimination of the administered uric acid owing to the large dose administered. The questions are therefore raised as to what enzyme systems are involved, the mechanism of uric acid oxidation, and the end-products of this degradation. In the present investigation it will be shown that uric acid can be oxidized in the presence of the following enzyme systems: lactoperoxidase, verdoperoxidase, horseradish peroxidase, and catalase. Some aspects of the mechanism of these oxidations have been studied and the end-products identified.