Mechanisms of acetohydroxyacid synthases

David M. Chipman, Ronald G. Duggleby, Kai Tittmann

Research output: Contribution to journalReview articlepeer-review

91 Scopus citations


Acetohydroxyacid synthases are thiamin diphosphate- (ThDP-) dependent biosynthetic enzymes found in all autotrophic organisms. Over the past 4-5 years, their mechanisms have been clarified and illuminated by protein crystallography, engineered mutagenesis and detailed single-step kinetic analysis. Pairs of catalytic subunits form an intimate dimer containing two active sites, each of which lies across a dimer interface and involves both monomers. The ThDP adducts of pyruvate, acetaldehyde and the product acetohydroxyacids can be detected quantitatively after rapid quenching. Determination of the distribution of intermediates by NMR then makes it possible to calculate individual forward unimolecular rate constants. The enzyme is the target of several herbicides and structures of inhibitor-enzyme complexes explain the herbicide-enzyme interaction.

Original languageEnglish
Pages (from-to)475-481
Number of pages7
JournalCurrent Opinion in Chemical Biology
Issue number5
StatePublished - 1 Jan 2005

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry


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