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Metabolic Modeling Tutorial
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MetaCyc Enzyme: glutaminase B

Species: Escherichia coli K-12 substr. MG1655

Subunit composition of glutaminase B = [glutaminase B monomer]4

Summary:
Two glutaminases were purified from E. coli B. They differ in their pH optima and regulation [Prusiner71]. Glutaminase B is active at neutral and alkaline pH [Prusiner76], and the enzyme is constitutive [Prusiner75].

Molecular Weight of Polypeptide: 22.5 kD (from nucleotide sequence)

Molecular Weight of Multimer: 90.0 kD (experimental) [Prusiner76]

pI: 5.4 [Prusiner76]

Gene-Reaction Schematic: ?

Credits:
Imported from EcoCyc 16-Sep-2014 by Paley S , SRI International


Enzymatic reaction of: glutaminase B

Synonyms: glutaminase, L-glutamine amidohydrolase

EC Number: 3.5.1.2

L-glutamine + H2O <=> L-glutamate + ammonium

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

Alternative Substrates [Comment 1]:

In Pathways: glutamine degradation I

Credits:
Imported from EcoCyc 16-Sep-2014 by Paley S , SRI International

Summary:
The E. coli B enzyme was purified and characterized [Prusiner76, Prusiner76a, Prusiner76b].

Activators (Allosteric): L-glutamate [Prusiner76a, Prusiner76b]

Activators (Unknown Mechanism): borate [Prusiner76a] , Mg2+ [Prusiner76b] , Mn2+ [Prusiner76b] , Ca2+ [Prusiner76b] , AMP [Prusiner76b] , diphosphate [Prusiner76b] , PPPi [Prusiner76b]

Inhibitors (Competitive): L-glutamate [Prusiner76a, Comment 2]

Inhibitors (Unknown Mechanism): borate [Prusiner76a] , ATP [Prusiner76b] , ADP [Prusiner76b] , adenosine tetraphosphate [Prusiner76b] , NAD+ [Prusiner76b] , NADH [Prusiner76b] , NADP+ [Prusiner76b] , NADPH [Prusiner76b]

pH(opt): 7.1-9 [Prusiner76]


References

Prusiner71: Prusiner S, Stadtman ER (1971). "On the regulation of glutaminase in E. coli: metabolite control." Biochem Biophys Res Commun 45(6);1474-81. PMID: 4399639

Prusiner75: Prusiner S (1975). "Regulation of glutaminase levels in Escherichia coli." J Bacteriol 123(3);992-9. PMID: 239927

Prusiner76: Prusiner S, Davis JN, Stadtman ER (1976). "Regulation of glutaminase B in Escherichia coli. I. Purification, properties, and cold lability." J Biol Chem 1976;251(11);3447-56. PMID: 6454

Prusiner76a: Prusiner S, Stadtman ER (1976). "Regulation of glutaminase B in Escherichia coli. II. Modulaltion of activity by carbosylate and borate ions." J Biol Chem 1976;251(11);3457-62. PMID: 776969

Prusiner76b: Prusiner S, Stadtman ER (1976). "Regulation of glutaminase B in Escherichia coli. III. Control by nucleotides and divalent cations." J Biol Chem 1976;251(11);3463-9. PMID: 776970


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Thu Nov 27, 2014, BIOCYC13A.