Acetohydroxyacid synthase: A new enzyme for chiral synthesis of R-phenylacetylcarbinol

Stanislav Engel, Maria Vyazmensky, Shimona Geresh, Ze'ev Barak, David M. Chipman

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


We have found that acetohydroxyacid synthase (AHAS) is an efficient catalyst for the enantiospecific (≥98% enantiomeric excess) synthesis of (R)-phenylacetylcarbinol (R-PAC) from pyruvate and benzaldehyde, despite the fact that its normal physiological role is synthesis of (S)-acetohydroxyacids from pyruvate and a second ketoacid. (R)-phenylacetylcarbinol is the precursor of important drugs having α and β adrenergic properties, such as L-ephedrine, pseudoephedrine, and norephedrin. It is currently produced by whole-cell fermentations, but the use of the isolated enzyme pyruvate decarboxylase (PDC) for this purpose is the subject of active research and development efforts. Some of the AHAS isozymes of Escherichia coli have important advantages compared to PDC, including negligible acetaldehyde formation and high conversion of substrates (both pyruvate and benzaldehyde) to PAC. Acetohydroxyacid synthase isozyme I is particularly efficient. The reaction is not limited to condensation of pyruvate with benzaldehyde and other aromatic aldehydes may be used.

Original languageEnglish
Pages (from-to)833-840
Number of pages8
JournalBiotechnology and Bioengineering
Issue number7
StatePublished - 30 Sep 2003


  • Acetolactate synthase
  • Benzaldehyde
  • Biocatalysis
  • Chiral
  • Enantiomeric excess
  • Hydroxyketone
  • Pyruvate
  • Pyruvate decarboxylase
  • Stereospecificity
  • Thiamin diphosphate

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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