Purine Nucleotide Catabolism in Rat Liver. Certain Preliminary Aspects of Uricase Reaction

Abstract

We investigated the mechanism of action of uricase, which oxidizes uric acid to allantoin, in the rat. Allantoin may decompose chemically to urea and hydantoin, containing the carbons in positions 2 and 8 of the purine ring, respectively. These carbons are derived by formylation, catalyzed by formyltransferase, in two reactions of de novo synthesis. Since uric acid and allantoin are represented in equivalent amounts in the liver, we expected to find identical incorporation of radioactivity in C₂ and C₈ of both compounds after administration of ¹⁴C-formate. In the case of ¹⁴C-allantoin, this was true, but not for ¹⁴C-uric acid extracted from rat liver. We interpret these results through a series of experiments and considerations.

Keywords:

• Allantoin
• uric acid
• uricase

Notes

^a14C₈-uric acid was obtained from rat treated with commercial ¹⁴C₈-uric acid.

^a14C-uric acid was obtained from rat treated with ¹⁴C-formate.

^a14C-allantoin was obtained from rat treated with ¹⁴C-formate.