1nux
From Proteopedia
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| , resolution 1.6Å | |||||||
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| Ligands: | , , | ||||||
| Activity: | Fructose-bisphosphatase, with EC number 3.1.3.11 | ||||||
| Related: | 1NUW, 1NUY
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Fructose-1,6-Bisphosphatase Complex with Magnesium, Fructose-6-Phosphate, Phosphate and inhibitory concentrations of Potassium (200mM)
Overview
The hydrolysis of a phosphate ester can proceed through an intermediate of metaphosphate (dissociative mechanism) or through a trigonal bipryamidal transition state (associative mechanism). Model systems in solution support the dissociative pathway, whereas most enzymologists favor an associative mechanism for enzyme-catalyzed reactions. Crystals of fructose-1,6-bisphosphatase grow from an equilibrium mixture of substrates and products at near atomic resolution (1.3 A). At neutral pH, products of the reaction (orthophosphate and fructose 6-phosphate) bind to the active site in a manner consistent with an associative reaction pathway; however, in the presence of inhibitory concentrations of K+ (200 mm), or at pH 9.6, metaphosphate and water (or OH-) are in equilibrium with orthophosphate. Furthermore, one of the magnesium cations in the pH 9.6 complex resides in an alternative position, and suggests the possibility of metal cation migration as the 1-phosphoryl group of the substrate undergoes hydrolysis. To the best of our knowledge, the crystal structures reported here represent the first direct observation of metaphosphate in a condensed phase and may provide the structural basis for fundamental changes in the catalytic mechanism of fructose-1,6-bisphosphatase in response to pH and different metal cation activators.
About this Structure
1NUX is a Single protein structure of sequence from Sus scrofa. Full crystallographic information is available from OCA.
Reference
Metaphosphate in the active site of fructose-1,6-bisphosphatase., Choe JY, Iancu CV, Fromm HJ, Honzatko RB, J Biol Chem. 2003 May 2;278(18):16015-20. Epub 2003 Feb 20. PMID:12595528
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