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Literature summary for 2.2.1.6 extracted from
- Acetohydroxyacid synthase isozyme I from Escherichia coli has unique catalytic and regulatory properties (2006), Biochim. Biophys. Acta, 1760, 356-363.
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| isozyme I subunit-encoding genes ilvB and ilvN, DNA and amino acid sequence determination and analysis, expression of His-tagged holoenzyme or individual subunits in strain BL21 | Escherichia coli |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| benzaldehyde | inhibits isozyme AHAS II, not isozyme AHAS I | Escherichia coli |  |
| additional information | inhibition kinetics or recombinant wild.type and reconstituted isozymes AHAS I | Escherichia coli | |
| valine | isozyme AHAS I, cooperative feedback inhibition | Escherichia coli | |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| additional information | - |
additional information | kinetics or recombinant wild-type and reconstituted isozymes AHAS I, exclusive binding model | Escherichia coli | |
| 4 | - |
pyruvate | 37°C, reconstituted, recombinant holoenzyme | Escherichia coli | |
| 4.8 | - |
pyruvate | 37°C, recombinant holoenzyme | Escherichia coli | |
Metals/Ions
| Metals/Ions | Comment | Organism | Structure |
|---|---|---|---|
| Mg2+ | required | Escherichia coli | |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| additional information | Escherichia coli | mechanism of expression regulation, overview | ? | - |
? | |
| pyruvate | Escherichia coli | first step in the biosynthesis of valine, overview | 2-acetolactate + CO2 | - |
r | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Escherichia coli | - |
isozymes I-III, subunit-encoding genes ilvB and ilvN | - |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant His-tagged isozyme I holoenzyme or individual subunits from strain BL21 by affinity chromatography | Escherichia coli |
Reaction
| Reaction | Comment | Organism | Reaction ID |
|---|---|---|---|
| 2 pyruvate = 2-acetolactate + CO2 | the enzyme catalyzes the decarboxylation of bound pyruvate to form a hydroxyethyl-thiamine diphosphate anion/enamine intermediate, which normally reacts with a second molecule of an alpha-ketoacid to form an acetohydroxyacid, but can also perform several side reactions proceeding through the hydroxyethyl-thiamine diphosphate anion/enamine intermediate | Escherichia coli |
Renatured (Commentary)
| Renatured (Comment) | Organism |
|---|---|
| reconstitution of the holoenzyme from recombinantly expressed, purified subunits encoded by genes ilvB and ilvN | Escherichia coli |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| additional information | - |
- |
Escherichia coli |
| 60.5 | - |
reconstituted, recombinant holoenzyme | Escherichia coli |
| 63.6 | - |
recombinant holoenzyme | Escherichia coli |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| additional information | mechanism of expression regulation, overview | Escherichia coli | ? | - |
? | |
| additional information | acetohydroxybutyrate is preferably formed, isozyme AHAS I can also form peracetate from synthetic acetolactate | Escherichia coli | ? | - |
? | |
| pyruvate | - |
Escherichia coli | 2-acetolactate + CO2 | - |
r | |
| pyruvate | first step in the biosynthesis of valine, overview | Escherichia coli | 2-acetolactate + CO2 | - |
r | |
| pyruvate + benzaldehyde | stereospecific reaction, isozymes AHAS I and II | Escherichia coli | (R)-phenylacetylcarbinol + CO2 | - |
? | |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| acetohydroxyacid synthase | - |
Escherichia coli |
| AHAS | - |
Escherichia coli |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 37 | - |
assay at | Escherichia coli |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| FAD | - |
Escherichia coli | |
| thiamine diphosphate | dependent on | Escherichia coli | |
Ki Value [mM]
| Ki Value [mM] | Ki Value maximum [mM] | Inhibitor | Comment | Organism | Structure |
|---|---|---|---|---|---|
| 1.4 | - |
benzaldehyde | isozyme AHAS II | Escherichia coli | |
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