2eb4 | pdb_00002eb4

Crystal structure of apo-HpcG

spinqualitylabelsall models 2eb4, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2eb4 is a 5 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: NA, SCN Related: 2eb5, 2eb6 Gene: hpcG (Escherichia coli) Resources: FirstGlance, OCA, RCSB, PDBsum Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed HpcG catalyses the hydration of a carbon-carbon double bond without the aid of any cofactor other than a simple divalent metal ion such as Mg(2+). Since the substrate has a nearby carbonyl group, it is believed that it first isomerises to form a pair of conjugated double bonds in the enol tautomer before Michael addition of water. Previous chemical studies of the reaction, and that of the related enzyme MhpD, have failed to provide a clear picture of the mechanism. The substrate itself is unstable, preventing co-crystallisation or soaking of crystals, but oxalate is a strong competitive inhibitor. We have solved the crystal structure of the protein in the apo form, and with magnesium and oxalate bound. Modelling substrate into the active site suggests the attacking water molecule is not part of the metal coordination shell, in contrast to a previous proposal. Our model suggests that geometrically strained cis isomer intermediates do not lie on the reaction pathway, and that separate groups are involved in the isomerisation and hydration steps. Structure and mechanism of HpcG, a hydratase in the homoprotocatechuate degradation pathway of Escherichia coli.,Izumi A, Rea D, Adachi T, Unzai S, Park SY, Roper DI, Tame JR J Mol Biol. 2007 Jul 27;370(5):899-911. Epub 2007 May 10. PMID:17559873 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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