Mechanism of inactivation of Escherichia coli aspartate aminotransferase by (S)-4-amino-4,5-dihydro-2-furancarboxylic acid

Biochemistry. 2010 Dec 14;49(49):10507-15. doi: 10.1021/bi101325z. Epub 2010 Nov 15.


As a potential drug to treat neurological diseases, the mechanism-based inhibitor (S)-4-amino-4,5-dihydro-2-furancarboxylic acid (S-ADFA) has been found to inhibit the γ-aminobutyric acid aminotransferase (GABA-AT) reaction. To circumvent the difficulties in structural studies of a S-ADFA-enzyme complex using GABA-AT, l-aspartate aminotransferase (l-AspAT) from Escherichia coli was used as a model PLP-dependent enzyme. Crystal structures of the E. coli aspartate aminotransferase with S-ADFA bound to the active site were obtained via cocrystallization at pH 7.5 and 8. The complex structures suggest that S-ADFA inhibits the transamination reaction by forming adducts with the catalytic lysine 246 via a covalent bond while producing 1 equiv of pyridoxamine 5'-phosphate (PMP). Based on the structures, formation of the K246-S-ADFA adducts requires a specific initial binding configuration of S-ADFA in the l-AspAT active site, as well as deprotonation of the ε-amino group of lysine 246 after the formation of the quinonoid and/or ketimine intermediate in the overall inactivation reaction.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aspartate Aminotransferases / antagonists & inhibitors*
  • Aspartate Aminotransferases / chemistry
  • Aspartate Aminotransferases / metabolism
  • Crystallization
  • Escherichia coli / enzymology*
  • Escherichia coli Proteins / antagonists & inhibitors*
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / metabolism
  • Furans / chemistry
  • Furans / metabolism*
  • Thiophenes / chemistry
  • Thiophenes / metabolism


  • (S)-4-amino-4,5-dihydro-2-thiophenecarboxylic acid
  • Escherichia coli Proteins
  • Furans
  • Thiophenes
  • Aspartate Aminotransferases
  • 2-furoic acid

Associated data

  • PDB/3PA9
  • PDB/3PAA