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Literature summary for 6.3.1.2 extracted from

  • Clemente, M.T.; Marquez, A.J.
    Functional importance of Asp56 from the alpha-polypeptide of Phaseolus vulgaris glutamine synthetase: An essential residue for transferase but not for biosynthetic enzyme activity (1999), Eur. J. Biochem., 264, 453-460.
    View publication on PubMed
Search for more literature for 6.3.1.2

Cloned(Commentary)

Cloned (Comment) Organism
mutant and native enzymes expressed in Escherichia coli Phaseolus vulgaris

Protein Variants

Protein Variants Comment Organism
D56A complete loss of activity in reverse reaction, 83% of wild-type activity in forward reaction, salting out at much higher ammonium sulfate concentrations than wild type enzyme Phaseolus vulgaris
D56E complete loss of activity in reverse reaction, 65% of wild-type activity in forward reaction, salting out properties only slightly affected Phaseolus vulgaris

Inhibitors

Inhibitors Comment Organism Structure
2-mercaptoethanol no inhibition of wild type enzyme, inhibits activity of D56A and D56E mutant enzymes Phaseolus vulgaris
cysteine no inhibition of wild type enzyme, inhibits activity of D56A and D56E mutant enzymes Phaseolus vulgaris
dithioerythritol no inhibition of wild type enzyme, inhibits activity of D56A and D56E mutant enzymes Phaseolus vulgaris
p-hydroxymercuribenzoate complete inhibition of wild type and D56A mutant, 40% inhibition of D56E at 1 mM Phaseolus vulgaris

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.013
-
 NH4+ D56E mutant enzyme, pH 7.5, 37°C Phaseolus vulgaris
0.02
-
 NH4+ D56A mutant enzyme, pH 7.5, 37°C Phaseolus vulgaris
0.025
-
 NH4+ wild type enzyme, pH 7.5, 37°C Phaseolus vulgaris
0.3
-
 ATP wild type enzyme, pH 7.5, 37°C Phaseolus vulgaris
1
-
 ATP D56E mutant enzyme, pH 7.5, 37°C Phaseolus vulgaris
1.6
-
 ATP D56A mutant enzyme, pH 7.5, 37°C Phaseolus vulgaris
7
-
 L-glutamate wild type enzyme, pH 7.5, 37°C Phaseolus vulgaris
18
-
 L-glutamate D56E mutant enzyme, pH 7.5, 37°C Phaseolus vulgaris
38
-
 L-glutamate D56A mutant enzyme, pH 7.5, 37°C Phaseolus vulgaris

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
43000
-
 SDS-PAGE Phaseolus vulgaris
350000
-
 gel filtration Phaseolus vulgaris

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
ATP + glutamate + NH4+ Phaseolus vulgaris central enzyme of nitrogen metabolism, assimilation of ammonia ADP + phosphate + L-glutamine
-
 r

Organism

Organism UniProt Comment Textmining
Phaseolus vulgaris
-
-
-

Purification (Commentary)

Purification (Comment) Organism
recombinant enzymes Phaseolus vulgaris

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
ATP + glutamate + NH4+
-
 Phaseolus vulgaris ADP + phosphate + L-glutamine
-
 r
ATP + glutamate + NH4+ central enzyme of nitrogen metabolism, assimilation of ammonia Phaseolus vulgaris ADP + phosphate + L-glutamine
-
 r

Subunits

Subunits Comment Organism
octamer 8 * 43000, subunits by SDS-PAGE, native mass by gel filtration Phaseolus vulgaris
tetramer 4 * 43000, minor peak in gel filtration with a mass of 190000 detected for both mutant enzymes Phaseolus vulgaris

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
37
-
 forward reaction, wild-type and mutant enzymes Phaseolus vulgaris

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
7.5
-
 forward reaction, wild-type and mutant enzymes Phaseolus vulgaris