Input interpretation
urea cycle (human metabolic pathway)
Alternate names
Krebs-Henseleit cycle | Krebs ornithine cycle
Pathway topology
Pathway topology
Pathway components
| ammonia | ammonia anhydrous | ammonia gas | azane | nitro-sil | spirit of hartshorn | 17 g/mol | | NH_3 | carbamoyl-phosphate | carbamoyl-P | carbamyl-phosphate | 141 g/mol | | C_1H_4N_1O_5P_1 | L-ornithine | 132.2 g/mol | | C_5H_12N_2O_2 | L-citrulline | 175.2 g/mol | | C_6H_13N_3O_3 | L-arginino-succinate | N-(L-arginino)-succinate | arginino-succinate | 290.3 g/mol | | C_10H_18N_4O_6 | L-arginine | (S)-2-amino-5-guanidinopentanoic acid | 174.2 g/mol | | H_2NC(=NH)NH(CH_2)_3CH(NH_2)CO_2H
Pathway steps
| reaction ⟶ | + ATP + CO_2 + H_2O ⟶ + ADP + phosphate | carbamoyl-phosphate synthase (ammonia), mitochondrial precursor + ⟶ | + ⟶ + phosphate | ornithine carbamoyltransferase, mitochondrial precursor ⟶ | + ATP + L-aspartate ⟶ + AMP + diphosphate | argininosuccinate synthase ⟶ | ⟶ + fumarate | argininosuccinate lyase ⟶ | + H_2O ⟶ + urea | arginase II, mitochondrial precursor | arginase 1
Related pathways
| overlapping components proline biosynthesis V (from arginine) | citrulline biosynthesis | citrulline-nitric oxide cycle | arginine degradation VI (arginase 2 pathway) | arginine degradation I (arginase pathway) |