Snapshot of an Enzyme Reaction Intermediate in the Structure of the ATP-Mg2+-oxalate Ternary Complex of Escherichia Coli PEP Carboxykinase

Nat Struct Biol. 1996 Apr;3(4):355-63. doi: 10.1038/nsb0496-355.


We report the 1.8 A crystal structure of adenosine triphosphate (ATP)-magnesium-oxalate bound phosphoenolpyruvate carboxykinase (PCK) from Escherichia coli. ATP binding induces a 20 degree hinge-like rotation of the N- and C-terminal domains which closes the active-site cleft. PCK possesses a novel nucleotide-binding fold, particularly in the adenine-binding region, where the formation of a cis backbone torsion angle in a loop glycine residue promotes intimate contacts between the adenine-binding loop and adenine, while stabilizing a syn conformation of the base. This complex represents a reaction intermediate analogue along the pathway of the conversion of oxaloacetate to phosphoenolpyruvate, and provides insight into the mechanistic details of the chemical reaction catalysed by this enzyme.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / chemistry*
  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence
  • Binding Sites
  • Crystallography, X-Ray
  • Escherichia coli / enzymology*
  • Models, Molecular
  • Molecular Sequence Data
  • Oxalates / chemistry*
  • Oxalates / metabolism
  • Phosphoenolpyruvate Carboxykinase (GTP) / chemistry*
  • Phosphoenolpyruvate Carboxykinase (GTP) / metabolism
  • Protein Binding
  • Protein Conformation
  • Protein Folding
  • Protein Structure, Tertiary


  • Oxalates
  • Adenosine Triphosphate
  • Phosphoenolpyruvate Carboxykinase (GTP)