The uric acid cycle is a cyclic adaptation of the process used for mammalian purine catabolism. Inosine monophosphate (IMP) is formed which reacts with pyrophosphate to form hypoxanthine and 5-phosphoribosylpyrophosphate (PRPP). This reaction is catalysed by hypoxanthine phosphoribosyltransferase (EC 2.4.
