Structure and mechanism of anthocyanidin synthase from Arabidopsis thaliana

Structure. 2002 Jan;10(1):93-103. doi: 10.1016/s0969-2126(01)00695-5.


Flavonoids are common colorants in plants and have long-established biomedicinal properties. Anthocyanidin synthase (ANS), a 2-oxoglutarate iron-dependent oxygenase, catalyzes the penultimate step in the biosynthesis of the anthocyanin class of flavonoids. The crystal structure of ANS reveals a multicomponent active site containing metal, cosubstrate, and two molecules of a substrate analog (dihydroquercetin). An additional structure obtained after 30 min exposure to dioxygen is consistent with the oxidation of the dihydroquercetin to quercetin and the concomitant decarboxylation of 2-oxoglutarate to succinate. Together with in vitro studies, the crystal structures suggest a mechanism for ANS-catalyzed anthocyanidin formation from the natural leucoanthocyanidin substrates involving stereoselective C-3 hydroxylation. The structure of ANS provides a template for the ubiquitous family of plant nonhaem oxygenases for future engineering and inhibition studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / enzymology*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Binding Sites
  • Models, Molecular
  • Molecular Sequence Data
  • Molecular Structure
  • Oxygenases / chemistry*
  • Oxygenases / genetics
  • Oxygenases / metabolism*
  • Protein Structure, Tertiary*
  • Sequence Alignment


  • Arabidopsis Proteins
  • Oxygenases
  • anthocyanidin synthase