Abstract
Acetohydroxyacid synthase (Ec 2.2.1.6) catalyses the thiamine diphosphate-dependent reaction between two molecules of pyruvate yielding 2-acetolactacte and CO2. The enzyme will also utilise hydroxypyruvate with a k(cat) value that is 12% of that observed with pyruvate. When hydroxypyruvate is the substrate, the enzyme undergoes progressive inactivation with kinetics that are characteristic of suicide inhibition. It is proposed that the dihydroxyethyl-thiamine diphosphate intermediate can expel a hydroxide ion forming an enol that rearranges to a bound acetyl group.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acetolactate Synthase / antagonists & inhibitors*
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Acetolactate Synthase / metabolism
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Catalysis
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Escherichia coli / enzymology
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Flavin-Adenine Dinucleotide / metabolism
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Kinetics
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Pyruvates / pharmacology*
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Recombinant Proteins / antagonists & inhibitors
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Recombinant Proteins / metabolism
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Substrate Specificity
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Thiamine Pyrophosphate / analogs & derivatives*
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Thiamine Pyrophosphate / metabolism
Substances
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Pyruvates
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Recombinant Proteins
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dihydroxyethylthiamine pyrophosphate
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Flavin-Adenine Dinucleotide
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hydroxypyruvic acid
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Acetolactate Synthase
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Thiamine Pyrophosphate