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Literature summary for 6.3.2.2 extracted from

  • Hamilton, D.; Wu, J.H.; Alaoui-Jamali, M.; Batist, G.
    A novel missense mutation in the gamma-glutamylcysteine synthetase catalytic subunit gene causes both decreased enzymatic activity and glutathione production (2003), Blood, 102, 725-730.
    View publication on PubMed
Search for more literature for 6.3.2.2

Cloned(Commentary)

Cloned (Comment) Organism
catalytic subunit DNA sequence determination and analysis, expression as His-tagged wild-type enzyme and mutant R127C in Rosetta cells, functional expression of wild-type and mutant enzyme in enzyme-deficient cells Homo sapiens

Protein Variants

Protein Variants Comment Organism
R127C naturally occuring mutation in patients with hemolytic anemia resulting from low erythrocyte enzyme levels, fibroblast cells from these patients bearing the mutation show 95% reduced enzyme activity and lowered Km for glutamate and aminobutyrate, as well as an increased Ki for GSH Homo sapiens

Inhibitors

Inhibitors Comment Organism Structure
GSH feedback inhibition, mutant R127C is not sensitive Homo sapiens

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.25
-
 L-alpha-aminobutyrate mutant R127C, pH 8.0, 37°C Homo sapiens
0.63
-
 L-Glu mutant R127C, pH 8.0, 37°C Homo sapiens
2.39
-
 L-alpha-aminobutyrate wild-type enzyme, pH 8.0, 37°C Homo sapiens
7.16
-
 L-Glu wild-type enzyme, pH 8.0, 37°C Homo sapiens

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+
-
 Homo sapiens

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
ATP + L-Glu + L-Cys Homo sapiens first and rate limiting step in GSH biosynthesis, rare hereditary enzyme deficiency is associated with low erythrocyte levels of the enzyme leading to hemolytic anemia ADP + phosphate + gamma-L-Glu-L-Cys
-
 ?

Organism

Organism UniProt Comment Textmining
Homo sapiens
-
-
-

Purification (Commentary)

Purification (Comment) Organism
recombinant His-tagged wild-type and mutant R127C enzyme from Rosetta cells Homo sapiens

Reaction

Reaction Comment Organism Reaction ID
ATP + L-glutamate + L-cysteine = ADP + phosphate + gamma-L-glutamyl-L-cysteine substrate binding mechanism and catalytic site structure determination and analysis, Arg127 and conserved Cys249 are involved Homo sapiens
a

Source Tissue

Source Tissue Comment Organism Textmining
fibroblast dermal Homo sapiens
-

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
0.44
-
 purified mutant R127C enzyme, substrates L-glutamate and L-alpha-aminobutyrate Homo sapiens
8.86
-
 purified wild-type enzyme, substrates L-glutamate and L-alpha-aminobutyrate Homo sapiens

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
ATP + L-Glu + L-alpha-aminobutyrate
-
 Homo sapiens ADP + phosphate + gamma-L-Glu-L-alpha-aminobutyrate
-
 ?
ATP + L-Glu + L-Cys
-
 Homo sapiens ADP + phosphate + gamma-L-Glu-L-Cys
-
 ?
ATP + L-Glu + L-Cys first and rate limiting step in GSH biosynthesis, rare hereditary enzyme deficiency is associated with low erythrocyte levels of the enzyme leading to hemolytic anemia Homo sapiens ADP + phosphate + gamma-L-Glu-L-Cys
-
 ?

Subunits

Subunits Comment Organism
More the holoenzyme consists of a heavy catalytic and a light modifier subunit, i.e. gamma-GCSH and gamma-GCSL, protein modeling Homo sapiens

Synonyms

Synonyms Comment Organism
gamma-GCS
-
 Homo sapiens
gamma-Glutamylcysteine synthetase
-
 Homo sapiens

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
37
-
 assay at Homo sapiens

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8
-
 assay at Homo sapiens

Cofactor

Cofactor Comment Organism Structure
ATP dependent on Homo sapiens

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.45
-
 GSH wild-type enzyme, pH 8.0, 37°C Homo sapiens
1000
-
 GSH above, mutant R127C, pH 8.0, 37°C Homo sapiens