BIOSYNTHESIS 



257 



O 

 H2N — C ~ O — PO(OH)2 



carbamylphosphate 



HN — C = O 



I I 

 O = C CH 



I II 

 HN — C — COOH 



orotic acid 



PRPP 



^PP 



HN — C = O 



I I 

 O =C CH 



1 II 

 N — C — COOH 



R — 5' — O — PO(OH)2 



orotidine — 5' — PO4 



NHa 



HN — CNH2 



I I 

 O = C CH 



1 II 

 N — C — COOH 



I 

 R — 5' — O — OP(OH)8 



aspartate 



H3PO4 



DPN 



2H 



3^ 



^ 



CO, 



H2N COOH 



I I 



^ = C CHa 



I I 



HN — CH — COOH 



ureidosuccinic acid 

 (carbamylaspartic acid) 



— H.O 



HN — C = O 



I I 

 O = C CH2 



I I 



HN — CH — COOH 



dihydroorotic acid 



HN — C = O 



I I 

 ^ O = C CH 



I II 

 N — CH 



R — 5' — O — PO(OH)3 



uridine monophosphate 



HN — CNH2 



I I 

 ->- O = C CH 



I il 

 N — CH 



I 

 R — 5 — O — PO(OH), 



cytidine monophosphate 



Fig. 75. 



