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Literature summary extracted from

  • Bigelis, R.; Umbarger, H.E.
    Yeast alpha-isopropylmalate isomerase. Factors affecting enzyme stability and enzyme activity (1976), J. Biol. Chem., 251, 3545-3552.
    View publication on PubMed

General Stability

EC Number General Stability Organism
4.2.1.33 stabilized by high concentrations of glycerol and ammonium sulfate which also inhibit activity, half-life with 50% glycerol, 2.07 M ammonium sulfate, and 30% glycerol plus 830 mM ammonium sulfate: 50 h, 57 h, and 90 h, respectively, instead of 2-3 h without, stabilization probably due to changes in intramolecular interactions Saccharomyces cerevisiae

Inhibitors

EC Number Inhibitors Comment Organism Structure
4.2.1.33 (NH4)2SO4 recovery after restoration of lower ionic strength shows hysteresis effect Saccharomyces cerevisiae
4.2.1.33 1,10-phenanthroline 16% inhibition at 0.1 mM Saccharomyces cerevisiae
4.2.1.33 8-hydroxyquinolinesulfonate 16% inhibition at 0.1 mM Saccharomyces cerevisiae
4.2.1.33 K3PO4
-
 Saccharomyces cerevisiae
4.2.1.33 KCl
-
 Saccharomyces cerevisiae
4.2.1.33 KCN inactivation prevented by ammonium sulfate Saccharomyces cerevisiae
4.2.1.33 KF most potent inhibitor Saccharomyces cerevisiae
4.2.1.33 additional information inhibition at pH 4.5-5.0, reactivation at neutral pH Saccharomyces cerevisiae

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
4.2.1.33 0.0216
-
 dimethylcitraconate
-
 Saccharomyces cerevisiae

Molecular Weight [Da]

EC Number Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
4.2.1.33 90000
-
 sucrose density gradient centrifugation, gel filtration Saccharomyces cerevisiae

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
4.2.1.33 2-isopropylmaleate + H2O Saccharomyces cerevisiae second of three reactions of leucine biosynthesis ?
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
4.2.1.33 Saccharomyces cerevisiae
-
-
-

Purification (Commentary)

EC Number Purification (Comment) Organism
4.2.1.33
-
 Saccharomyces cerevisiae

Reaction

EC Number Reaction Comment Organism Reaction ID
4.2.1.33 (2R,3S)-3-isopropylmalate = 2-isopropylmaleate + H2O mechanism, equilibrium in vitro favors reaction opposite the direction of leucine biosynthesis Saccharomyces cerevisiae
a

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
4.2.1.33 2-isopropylmaleate + H2O
-
 Saccharomyces cerevisiae 3-isopropylmalate
-
 ?
4.2.1.33 2-isopropylmaleate + H2O second of three reactions of leucine biosynthesis Saccharomyces cerevisiae ?
-
 ?
4.2.1.33 3-isopropylmalate
-
 Saccharomyces cerevisiae 2-isopropylmaleate + H2O
-
 ?
4.2.1.33 dimethylcitraconate
-
 Saccharomyces cerevisiae ?
-
 ?

Subunits

EC Number Subunits Comment Organism
4.2.1.33 monomer 1*90000, SDS-PAGE Saccharomyces cerevisiae

Temperature Stability [°C]

EC Number Temperature Stability Minimum [°C] Temperature Stability Maximum [°C] Comment Organism
4.2.1.33 additional information
-
 very heat sensitive, high ionic strenght stabilizes enzyme against heat inactivation Saccharomyces cerevisiae
4.2.1.33 55
-
 half-life: 4.5 h, in stabilizing ammonium sulfate buffer Saccharomyces cerevisiae
4.2.1.33 62
-
 half-life: 1 min, in stabilizing ammonium sulfate buffer Saccharomyces cerevisiae

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
4.2.1.33 6.8
-
-
 Saccharomyces cerevisiae
4.2.1.33 7 9
-
 Saccharomyces cerevisiae

pH Stability

EC Number pH Stability pH Stability Maximum Comment Organism
4.2.1.33 6
-
 unstable at pH 7.0 or above Saccharomyces cerevisiae