Snapshot of an enzyme reaction intermediate in the structure of the ATP-Mg2+-oxalate ternary complex of Escherichia coli PEP carboxykinase.
Tari, L.W., Matte, A., Pugazhenthi, U., Goldie, H., Delbaere, L.T.(1996) Nat Struct Biol 3: 355-363
- PubMed: 8599762 
- DOI: https://doi.org/10.1038/nsb0496-355
- Primary Citation of Related Structures:  
1AYL - PubMed Abstract: 
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.
Organizational Affiliation: 
Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.