TRACING AND IDENTIFICATION OF URICASE REACTION INTERMEDIATES - A DIRECT C-13-NMR ISOTOPE-LABELING EVIDENCE

The C-13-NMR spectra are characteristic and provide a convenient method to chart the pathway of uricase-catalysed oxidation of [5-C-13]urate (1) to [4-C-13]allantoin (5); 5-hydroxy[5-C-13]isouric acid (2), its ring-opened derivative 3, and [4-C-13]allantoin-5-carboxylate (4) were identified as consecutive intermediates in D2O/phosphate buffer (pD 7.2).