Activating Compound | Comment | Organism | Structure |
---|---|---|---|
N-acetylglutamate | carbamoyl-phosphate synthase III: requirement for N-acetylglutamate | Squalus acanthias | |
N-acetylglutamate | carbamoyl-phosphate synthase II: no requirement for N-acetylglutamate | Mammalia | |
N-acetylglutamate | carbamoyl-phosphate synthase II: no requirement for N-acetylglutamate | Escherichia coli | |
NEM | 250fold activation of glutaminase activity. Irreversible inactivation of synthetase activity | Escherichia coli | |
Orn | activates | Escherichia coli | |
thiol | required for Gln-dependent activity | Escherichia coli |
Cloned (Comment) | Organism |
---|---|
- |
Escherichia coli |
Protein Variants | Comment | Organism |
---|---|---|
C269G | Cys269Gly and Cys269Ser mutants bind significant amounts of Gln but do not hydrolyze Gln. The mutants are able to catalyze carbamoyl-phosphate formation with NH4+ as nitrogen donor, at a rate equal to that of the wild type enzyme. The mutant enzyme catalyzes ATP synthesis from ADP and carbamoyl phosphate at the usual rates. Substantial increase in bicarbonate-dependent ATPase | Escherichia coli |
C269S | Cys269Gly and Cys269Ser mutants bind significant amounts of Gln but do not hydrolyze Gln. The mutants are able to catalyze carbamoyl-phosphate formation with NH4+ as nitrogen donor, at a rate equal to that of the wild type enzyme. The mutant enzyme catalyzes ATP synthesis from ADP and carbamoyl phosphate at the usual rates. Substantial increase in bicarbonate-dependent ATPase | Escherichia coli |
General Stability | Organism |
---|---|
treatment with 1 M potassium thiocyanate results in reversible dissociation into its subunits which retain catalytic activity | Escherichia coli |
Inhibitors | Comment | Organism | Structure |
---|---|---|---|
Alkyl hydrazines | inhibits Gln-dependent activity, but not NH4+-dependent activity | Escherichia coli | |
H2O2 | 0.2 mM, inhibits Gln-dependent activity. No effect on the activity with NH4+ in carbamoyl-phosphate synthase reaction | Escherichia coli | |
hydroxylamine | inhibits Gln-dependent activity, but not NH4+-dependent activity; the inhibitory effect is much greater at pH 9 than at pH 6 | Escherichia coli | |
L-2-Amino-4-oxo-5-chloropentanoate | selective inactivation of Gln-dependent activity | Escherichia coli | |
NEM | irreversible inactivation of synthetase activity. Increase of glutaminase activity | Escherichia coli | |
potassium cyanate | inhibits Gln-dependent activity, but not NH4+-dependent activity | Escherichia coli | |
UMP | - |
Escherichia coli |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.38 | - |
L-Gln | - |
Escherichia coli | |
93 | - |
NH4+ | - |
Escherichia coli |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
cytosol | - |
Mammalia | 5829 | - |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
K+ | required for maximal activity | Escherichia coli | |
Mg2+ | free Mg2+ is required in addition to MgATP2- | Escherichia coli | |
Mn2+ | maximal activity at concentration of Mn2+ approximately equal to the ATP concentration | Escherichia coli | |
NH4+ | can replace K+ in activation | Escherichia coli |
Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
---|---|---|---|
40000 | - |
1 * 40000, subunit contains the binding site for glutamine, + 1 * 133000, subunit contains the binding sites for NH4+, HCO3-, ATP, and the allosteric effectors. The light and heavy subunits are encoded by the genetically linked car A and car B genes, respectively | Escherichia coli |
133000 | - |
1 * 40000, subunit contains the binding site for glutamine, + 1 * 133000, subunit contains the binding sites for NH4+, HCO3-, ATP, and the allosteric effectors. The light and heavy subunits are encoded by the genetically linked car A and car B genes, respectively | Escherichia coli |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
ATP + L-Gln + HCO3- | Elasmobranchii | functions in the synthesis of urea used in osmoregulation | ? | - |
? | |
ATP + L-Gln + HCO3- | Mammalia | catalyzes the first step of de novo pyrimidine biosynthesis | ? | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Agaricus bisporus | - |
- |
- |
Elasmobranchii | - |
- |
- |
Escherichia coli | - |
- |
- |
Fresh-water teleost | - |
- |
- |
Mammalia | - |
- |
- |
Squalus acanthias | - |
- |
- |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
2 ATP + L-glutamine + hydrogencarbonate + H2O = 2 ADP + phosphate + L-glutamate + carbamoyl phosphate | mechanism, formation of enzyme-bound carboxy phosphate | Escherichia coli |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
2 ATP + L-Gln + HCO3- | - |
Mammalia | 2 ADP + phosphate + L-Glu + carbamoyl phosphate | - |
? | |
2 ATP + L-Gln + HCO3- | - |
Squalus acanthias | 2 ADP + phosphate + L-Glu + carbamoyl phosphate | - |
? | |
2 ATP + L-Gln + HCO3- | - |
Elasmobranchii | 2 ADP + phosphate + L-Glu + carbamoyl phosphate | - |
? | |
2 ATP + L-Gln + HCO3- | - |
Fresh-water teleost | 2 ADP + phosphate + L-Glu + carbamoyl phosphate | - |
? | |
2 ATP + L-Gln + HCO3- | - |
Agaricus bisporus | 2 ADP + phosphate + L-Glu + carbamoyl phosphate | - |
? | |
2 ATP + L-Gln + HCO3- | overall reaction is irreversible | Escherichia coli | 2 ADP + phosphate + L-Glu + carbamoyl phosphate | - |
? | |
2 ATP + NH4+ + HCO3- | - |
Escherichia coli | 2 ADP + phosphate + carbamoyl phosphate | - |
? | |
ATP + L-Gln + HCO3- | functions in the synthesis of urea used in osmoregulation | Elasmobranchii | ? | - |
? | |
ATP + L-Gln + HCO3- | catalyzes the first step of de novo pyrimidine biosynthesis | Mammalia | ? | - |
? |
Subunits | Comment | Organism |
---|---|---|
dimer | 1 * 40000, subunit contains the binding site for glutamine, + 1 * 133000, subunit contains the binding sites for NH4+, HCO3-, ATP, and the allosteric effectors. The light and heavy subunits are encoded by the genetically linked car A and car B genes, respectively | Escherichia coli |
More | - |
Mammalia |
More | enzyme can exist in different monomer conformations and states of association | Escherichia coli |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
4.2 | - |
and a second optimum at pH 9.5, glutaminase activity | Escherichia coli |
7.8 | 8.2 | - |
Escherichia coli |
9.5 | - |
and a second optimum at pH 4.2, glutaminase activity | Escherichia coli |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
IMP | stimulates | Escherichia coli |