Evidence supporting a cis-enediol-based mechanism for Pyrococcus furiosus phosphoglucose isomerase

J Mol Biol. 2006 May 19;358(5):1353-66. doi: 10.1016/j.jmb.2006.03.015. Epub 2006 Mar 24.


The enzymatic aldose ketose isomerisation of glucose and fructose sugars involves the transfer of a hydrogen between their C1 and C2 carbon atoms and, in principle, can proceed through either a direct hydride shift or via a cis-enediol intermediate. Pyrococcus furiosus phosphoglucose isomerase (PfPGI), an archaeal metalloenzyme, which catalyses the interconversion of glucose 6-phosphate and fructose 6-phosphate, has been suggested to operate via a hydride shift mechanism. In contrast, the structurally distinct PGIs of eukaryotic or bacterial origin are thought to catalyse isomerisation via a cis-enediol intermediate. We have shown by NMR that hydrogen exchange between substrate and solvent occurs during the reaction catalysed by PfPGI eliminating the possibility of a hydride-shift-based mechanism. In addition, kinetic measurements on this enzyme have shown that 5-phospho-d-arabinonohydroxamate, a stable analogue of the putative cis-enediol intermediate, is the most potent inhibitor of the enzyme yet discovered. Furthermore, determination and analysis of crystal structures of PfPGI with bound zinc and the substrate F6P, and with a number of competitive inhibitors, and EPR analysis of the coordination of the metal ion within PfPGI, have suggested that a cis-enediol intermediate-based mechanism is used by PfPGI with Glu97 acting as the catalytic base responsible for isomerisation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalytic Domain
  • Crystallography, X-Ray
  • Electron Spin Resonance Spectroscopy
  • Enzyme Inhibitors / pharmacology
  • Glucose-6-Phosphate Isomerase / antagonists & inhibitors
  • Glucose-6-Phosphate Isomerase / chemistry*
  • Glucose-6-Phosphate Isomerase / metabolism*
  • Hydrogen / chemistry
  • Hydroxamic Acids / chemistry
  • Hydroxamic Acids / metabolism
  • Isomerism
  • Kinetics
  • Macromolecular Substances
  • Metals / chemistry
  • Models, Chemical
  • Models, Molecular
  • Nuclear Magnetic Resonance, Biomolecular
  • Pyrococcus furiosus / enzymology*
  • Stereoisomerism
  • Substrate Specificity
  • Sugar Phosphates / chemistry
  • Sugar Phosphates / metabolism


  • 5-phosphoarabinonohydroxamic acid
  • Enzyme Inhibitors
  • Hydroxamic Acids
  • Macromolecular Substances
  • Metals
  • Sugar Phosphates
  • Hydrogen
  • Glucose-6-Phosphate Isomerase

Associated data

  • PDB/ZGC0
  • PDB/ZGC1
  • PDB/ZGC2
  • PDB/ZGC3