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Literature summary for 2.2.1.6 extracted from

  • Vyazmensky, M.; Barak, Z.; Chipman, D.M., Eichler, J.
    Characterization of acetohydroxy acid synthase activity in the archaeon Haloferax volcanii (2000), Comp. Biochem. Physiol. B Biochem. Mol. Biol., 125, 205-210.
    View publication on PubMed

Inhibitors

Inhibitors Comment Organism Structure
EDTA dialysis against EDTA leads to an irreversible loss of activity Haloferax volcanii
L-isoleucine weakly Haloferax volcanii
L-valine inhibits to a maximal activity of approximately 50% at concentrations higher than 0.5 mM Haloferax volcanii
Mn2+ activates, high concentrations inhibit Haloferax volcanii
additional information leucine had negligible effect on the activity Haloferax volcanii
sulfometuron methyl
-
Haloferax volcanii

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
25.5
-
pyruvate pH 7.5, 37°C, in the presence of 3.5 M KCl Haloferax volcanii

Metals/Ions

Metals/Ions Comment Organism Structure
KCl maximal activity required KCl concentrations of greater than 3.5 M Haloferax volcanii
Mg2+ Mg2 is probably the natural cofactor of the enzyme. Halofgerax volcanii is thought to contain a high intracellular Mg2+ concentration, as its native habitat, the Dead Sea, contains 1.4 M MgCl2. The endogenous metal is apparently tightly-enough bound so that added Mg2+ does not stimulate the activity Haloferax volcanii
Mn2+ activates, high concentrations inhibit Haloferax volcanii
NaCl while raising the NaCl concentration from 1.5 to 3.5 M leads to an increase in enzyme activity, this increase is 3fold lower than that detected in the presence of optimal KCl levels Haloferax volcanii

Organism

Organism UniProt Comment Textmining
Haloferax volcanii
-
-
-
Haloferax volcanii DSM 3757
-
-
-

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
0.0043
-
substrate: pyruvate, pH 7.5, 37°C, in the presence of 3.5 M KCl Haloferax volcanii

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2 pyruvate
-
Haloferax volcanii 2-acetolactate + CO2
-
?
2 pyruvate
-
Haloferax volcanii DSM 3757 2-acetolactate + CO2
-
?

Synonyms

Synonyms Comment Organism
acetohydroxy acid synthase
-
Haloferax volcanii
AHAS
-
Haloferax volcanii

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
35 40
-
Haloferax volcanii
37
-
assay at Haloferax volcanii

Temperature Range [°C]

Temperature Minimum [°C] Temperature Maximum [°C] Comment Organism
25 45 activity can be detected between 25 and 45°C, with the 35–40°C range being optimal. A rapid loss in catalytic activity is observed above 45°C Haloferax volcanii

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
7.5
-
assay at Haloferax volcanii

Cofactor

Cofactor Comment Organism Structure
thiamine diphosphate required cofactor, apparent Km: 0.0088 mM Haloferax volcanii

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.005
-
sulfometuron methyl pH 7.5, 37°C, in the presence of 3.5 M KCl Haloferax volcanii