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Literature summary for 6.3.5.5 extracted from

  • Meister, A.
    Mechanism and regulation of the glutamine-dependent carbamyl phosphate synthetase of Escherichia coli (1989), Adv. Enzymol. Relat. Areas Mol. Biol., 62, 315-374.
    View publication on PubMed
Search for more literature for 6.3.5.5

Activating Compound

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(Commentary)

Cloned (Comment) Organism
-
 Escherichia coli

Protein Variants

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

General Stability Organism
treatment with 1 M potassium thiocyanate results in reversible dissociation into its subunits which retain catalytic activity Escherichia coli

Inhibitors

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 [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.38
-
 L-Gln
-
 Escherichia coli
93
-
 NH4+
-
 Escherichia coli

Localization

Localization Comment Organism GeneOntology No. Textmining
cytosol
-
 Mammalia 5829
-

Metals/Ions

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 [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/ Products (Substrates)

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

Organism UniProt Comment Textmining
Agaricus bisporus
-
-
-
Elasmobranchii
-
-
-
Escherichia coli
-
-
-
Fresh-water teleost
-
-
-
Mammalia
-
-
-
Squalus acanthias
-
-
-

Reaction

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
a

Substrates and Products (Substrate)

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

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

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

Cofactor Comment Organism Structure
IMP stimulates Escherichia coli