Category: catabolism
Terminal degradation of purine nucleotides (AMP, GMP) to uric acid. Hypoxanthine and guanine flow through xanthine on the way to uric acid via xanthine oxidase (XO) — the target of allopurinol + febuxostat for gout. Humans lack uricase (lost in primate evolution), so uric acid is the endpoint; in most other mammals uricase converts it to allantoin (the basis for pegloticase therapy in refractory gout — uricase enzyme replacement). Renal tubular reabsorption via URAT1 controls plasma urate setpoint — uricosurics (probenecid, lesinurad) inhibit URAT1.