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ENZYME entry: EC 6.3.4.16

Accepted Name
carbamoyl-phosphate synthase (ammonia).
Alternative Name(s)
carbamoylphosphate synthase (ammonia).
carbamoylphosphate synthetase (ammonia).
carbamoyl-phosphate synthetase (ammonia).
carbamoyl-phosphate synthetase I.
carbon-dioxide--ammonia ligase.
CPS I.
Reaction catalysed
2 ATP + hydrogencarbonate + NH4(+) <=> 2 ADP + carbamoyl phosphate + 2 H(+) + phosphate
Comment(s)
  • The enzyme catalyzes the first committed step in the urea cycle.
  • The reaction proceeds via three separate chemical reactions: phosphorylation of hydrogencarbonate to carboxyphosphate; a nucleophilic attack of ammonia on carboxyphosphate yielding carbamate; and the phosphorylation of carbamate forming carbamoyl phosphate.
  • Two moles of ATP are utilized for the synthesis of one molecule of carbamoyl phosphate, making the reaction essentially irreversible.
  • The enzyme requires the allosteric activator N-acetyl-L-glutamate.
  • Cf. EC 6.3.5.5.
  • Formerly EC 2.7.2.5.
Cross-references
BRENDA6.3.4.16
EC2PDB6.3.4.16
ExplorEnz6.3.4.16
PRIAM enzyme-specific profiles6.3.4.16
KEGG Ligand Database for Enzyme Nomenclature6.3.4.16
IUBMB Enzyme Nomenclature6.3.4.16
IntEnz6.3.4.16
MEDLINEFind literature relating to 6.3.4.16
MetaCyc6.3.4.16
Rhea expert-curated reactions6.3.4.16
UniProtKB/Swiss-Prot
P31327, CPSM_HUMAN;  Q91293, CPSM_LITCT;  Q8C196, CPSM_MOUSE;  
P07756, CPSM_RAT;  A5UK38, CPS_METS3;  

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