urate degradation KEGG:map00230 KEGG:map01100 KEGG:map01120 pathway PMID:16462750 GO:0019628 (S)-allantoin biosynthesis Degradation of uric acid, a key compound in the degradation of purines. The ureide pathway, which mediates the oxidative degradation of uric acid to (S)-allantoin, represents the late stage of purine catabolism in most organisms. The metabolism of uric acid has a pivotal role in transforming the nitrogen that is fixed in leguminous plants and also plays a crucial role in some bacteria under nitrogen-limited conditions. PMID:16485000 ureide pathway uric acid degradation PMID:17567580 UPa:UPA00394 ureide metabolism purine metabolism purine base degradation