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Literature summary for 2.3.3.13 extracted from

  • de Kraker, J.W.; Luck, K.; Textor, S.; Tokuhisa, J.G.; Gershenzon, J.
    Two Arabidopsis genes (IPMS1 and IPMS2) encode isopropylmalate synthase, the branchpoint step in the biosynthesis of leucine (2007), Plant Physiol., 143, 970-986.
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

Cloned (Comment) Organism
expression in Escherichia coli Arabidopsis thaliana

Protein Variants

Protein Variants Comment Organism
additional information knockout-mutant of isoform IPMS1 shows an increase in valine content, but no change in leucine content. Insertion mutation for isoform IPMS2 do not show any changes in soluble amino acid content. Arabidopsis thaliana

Inhibitors

Inhibitors Comment Organism Structure
EDTA 10 mM, complete loss of activity; 10 mM, complete loss of activity Arabidopsis thaliana
Leu inhibition of both enzymes reaches a maximum of 30% to 35% around 1 mM Leu; inhibition of both enzymes reaches a maximum of 30% to 35% around 1 mM Leu Arabidopsis thaliana
leucine 1 mM, 30-35% inhibition, both isoforms IPMS1 and IPMS2 Arabidopsis thaliana

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.016
-
acetyl-CoA
-
Arabidopsis thaliana
0.016
-
acetyl-CoA pH 8.0, isoform IPMS2 Arabidopsis thaliana
0.045
-
acetyl-CoA
-
Arabidopsis thaliana
0.045
-
acetyl-CoA pH 8.0, isoform IPMS1 Arabidopsis thaliana
0.279
-
2-oxo-3-methylbutanoate
-
Arabidopsis thaliana
0.279
-
2-oxo-3-methylbutanoate pH 8.0, isoform IPMS2 Arabidopsis thaliana
0.304
-
2-oxo-3-methylbutanoate
-
Arabidopsis thaliana
0.304
-
2-oxo-3-methylbutanoate pH 8.0, isoform IPMS1 Arabidopsis thaliana

Localization

Localization Comment Organism GeneOntology No. Textmining
chloroplast
-
Arabidopsis thaliana 9507
-

Metals/Ions

Metals/Ions Comment Organism Structure
K+ 4 mM, slight stimulation Arabidopsis thaliana
Mg2+ required, both isoforms IPMS1 and IPMS2 Arabidopsis thaliana
Mg2+ requires Mg2+ in millimolar concentrations Arabidopsis thaliana
Mn2+ after treatment with EDTA, 4 mM Mn2+ restores about 50% of the initial activity Arabidopsis thaliana
Mn2+ after tretment with EDTA, 4 mM Mn2+ restores about 50% of the initial activity Arabidopsis thaliana

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
62300
-
2 * 62300, calculated from nucleotide sequence Arabidopsis thaliana
63100
-
2 * 63100, calculated, isoform IPMS1 with His-tag Arabidopsis thaliana
64100
-
4 * 64100, calculated, isoform IPMS2 with His-tag Arabidopsis thaliana
64100
-
4 * 64100, calculated from nucleotide sequence Arabidopsis thaliana
124000
-
gel filtration Arabidopsis thaliana
124000
-
gel filtration, isoform IPMS1 Arabidopsis thaliana
280000
-
gel filtration Arabidopsis thaliana
280000
-
gel filtration, isoform IPMS2 Arabidopsis thaliana

Organism

Organism UniProt Comment Textmining
Arabidopsis thaliana
-
isoform IPMS1 and isoform IPMS2
-
Arabidopsis thaliana Q9C550
-
-
Arabidopsis thaliana Q9LPR4
-
-

Purification (Commentary)

Purification (Comment) Organism
-
Arabidopsis thaliana

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2-oxo-3-methylbutanoate + acetyl-CoA + H2O
-
Arabidopsis thaliana 3-hydroxy-4-methyl-3-carboxypentanoate + CoA
-
?
2-oxo-butanoate + acetyl-CoA + H2O isoform IPMS1, 112% of the rate with 2-oxo-3-methylbutanoate, isoform IPMS2, 97.5% of the rate with 2-oxo-3-methylbutanoate Arabidopsis thaliana 2-ethyl-2-hydroxysuccinic acid + CoA
-
?
2-oxo-butanoate + acetyl-CoA + H2O 112.2% of the activity with 2-oxo-3-methylbutanoate Arabidopsis thaliana 2-ethyl-2-hydroxysuccinic acid + CoA
-
?
2-oxo-butanoate + acetyl-CoA + H2O 97.5% of the activity with 2-oxo-3-methylbutanoate Arabidopsis thaliana 2-ethyl-2-hydroxysuccinic acid + CoA
-
?
2-oxo-n-pentanoate + acetyl-CoA + H2O isoform IPMS1, 27.2% of the rate with 2-oxo-3-methylbutanoate, isoform IPMS2, 33.8% of the rate with 2-oxo-3-methylbutanoate Arabidopsis thaliana 2-hydroxy-2-propylsuccinic acid + CoA
-
?
2-oxovalerate + acetyl-CoA + H2O 27.2% of the activity with 2-oxo-3-methylbutanoate Arabidopsis thaliana ?
-
?
2-oxovalerate + acetyl-CoA + H2O 33.8% of the activity with 2-oxo-3-methylbutanoate Arabidopsis thaliana ?
-
?
4-methylthio-2-oxopentanoate + acetyl-CoA + H2O
-
Arabidopsis thaliana ? + CoA at very low rate, reaction is involved in glucosinolate chain elongation ?
pyruvate + acetyl-CoA + H2O isoform IPMS1, 12.7% of the rate with 2-oxo-3-methylbutanoate, isoform IPMS2, 15.7% of the rate with 2-oxo-3-methylbutanoate Arabidopsis thaliana 2-hydroxy-2-methylsuccinic acid + CoA
-
?
pyruvate + acetyl-CoA + H2O 12.7% of the activity with 2-oxo-3-methylbutanoate Arabidopsis thaliana 2-hydroxy-2-methylsuccinic acid + CoA
-
?
pyruvate + acetyl-CoA + H2O 15.7% of the activity with 2-oxo-3-methylbutanoate Arabidopsis thaliana 2-hydroxy-2-methylsuccinic acid + CoA
-
?

Subunits

Subunits Comment Organism
dimer 2 * 63100, calculated, isoform IPMS1 with His-tag Arabidopsis thaliana
dimer 2 * 62300, calculated from nucleotide sequence Arabidopsis thaliana
tetramer 4 * 64100, calculated, isoform IPMS2 with His-tag Arabidopsis thaliana
tetramer 4 * 64100, calculated from nucleotide sequence Arabidopsis thaliana

Synonyms

Synonyms Comment Organism
2-isopropylmalate synthase 1, chloroplastic
-
Arabidopsis thaliana
2-isopropylmalate synthase 2, chloroplastic
-
Arabidopsis thaliana
IPMS1
-
Arabidopsis thaliana
IPMS2
-
Arabidopsis thaliana

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
1.9
-
acetyl-CoA
-
Arabidopsis thaliana
1.9
-
acetyl-CoA pH 8.0, isoform IPMS2 Arabidopsis thaliana
2.2
-
acetyl-CoA
-
Arabidopsis thaliana
2.2
-
acetyl-CoA pH 8.0, isoform IPMS1 Arabidopsis thaliana
2.3
-
2-oxo-3-methylbutanoate
-
Arabidopsis thaliana
2.3
-
2-oxo-3-methylbutanoate pH 8.0, isoform IPMS2 Arabidopsis thaliana
2.4
-
2-oxo-3-methylbutanoate
-
Arabidopsis thaliana
2.4
-
2-oxo-3-methylbutanoate pH 8.0, isoform IPMS1 Arabidopsis thaliana

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8.5
-
-
Arabidopsis thaliana
8.5
-
both isoforms IPMS1 and IPMS2 Arabidopsis thaliana