Dephosphorylation.O Excreted by Pi GMP nosine HNO Dephosphorylation HoO HgO -OH Uric acid Primates, birds reptiles, insects Deamination HO Guanosine Inosine 402+HO te oxdase Deribosylation h,o Hao Deribosylatio cO Ribose Ribe NHg C c-o Allantoin Most mammals HN HN Hy ypoxanthin °°首首(尿囊素) (keto form) H2N N H2 H2O xanthinekH20+O% oxidase,Hyo NH2CO0 NH2 NH: Oxidatio Allanton Bony fishes Deamination guanine 、黄嘌呤) HO (尿囊酸) HO N COO CHO xanthine H,0 +O2 oxidase →H2O2 Oxidatio Amphibians, Urea cartilaginous 2 H2N-C-NHg HN 2H20 -OH →2 HO N Mar ANHA invertebrates Uric acid 尿(黄嘌呤) (尿酸) (尿囊素） (尿囊酸) Dephosphorylation Dephosphorylation Deamination Deamination Deribosylation Deribosylation Oxidation Oxidation