Ligases;
Forming carbon-nitrogen bonds;
Other carbon-nitrogen ligases
BRITE hierarchy

UTP:L-glutamine amido-ligase (ADP-forming)

ATP + UTP + L-glutamine = ADP + phosphate + CTP + L-glutamate (overall reaction) [RN:R00573];
(1a) L-glutamine + H2O = L-glutamate + NH3 [RN:R00256];
(1b) ATP + UTP + NH3 = ADP + phosphate + CTP [RN:R00571]

R00256 R00571 R00573
Reaction

ATP [CPD:C00002];
UTP [CPD:C00075];
L-glutamine [CPD:C00064];
H2O [CPD:C00001];
NH3 [CPD:C00014]

The enzyme contains three functionally distinct sites: an allosteric GTP-binding site, a glutaminase site where glutamine hydrolysis occurs (cf. EC 3.5.1.2, glutaminase), and the active site where CTP synthesis takes place. The reaction proceeds via phosphorylation of UTP by ATP to give an activated intermediate 4-phosphoryl UTP and ADP [4,5]. Ammonia then reacts with this intermediate generating CTP and a phosphate. The enzyme can also use ammonia from the surrounding solution [3,6].

EC 6.3.4.2 created 1961, modified 2013