H2O 5-nucleotidase GMP Adenosine H2O H2O P Guanosine Inosine H2O nucleosidase nucleosidase Ribose HN Hypoxanthine (keto form) H2N N H, H20+o H2O (enol form) HO N xanthine H2o+ O2 H2O2 OH HO N Uric acid