1kcb

Crystal Structure of a NO-forming Nitrite Reductase Mutant: an Analog of a Transition State in Enzymatic Reaction

spinqualitylabelsall models 1kcb, resolution 1.65Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1kcb is a 1 chain structure with sequence from Achromobacter cycloclastes. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.65Å Ligands: CU Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function NIR_ACHCY 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 I257E was obtained by site directed mutagenesis of nitrite reductase from Achromobacter cycloclastes. The mutant has no enzyme activity. Its crystal structure determined at 1.65A resolution shows that the side-chain carboxyl group of the mutated residue, Glu257, coordinates with the type 2 copper in the mutant and blocks the contact between the type 2 copper and its solvent channel, indicating that the accessibility of the type 2 copper is essential for maintaining the activity of nitrite reductase. The carboxylate is an analog of the substrate, nitrite, but the distances between the type 2 copper and the two oxygen atoms of the side-chain carboxyl group are reversed in comparison to the binding of nitrite to the native enzyme. In the mutant, both the type 2 copper and the N epsilon atom on the imidazole ring of its coordinated residue His135 move in the substrate binding direction relative to the native enzyme. In addition, an EPR study showed that the type 2 copper in the mutant is in a reduced state. We propose that mutant I257E is in a state corresponding to a transition state in the enzymatic reaction. Crystal structure of a NO-forming nitrite reductase mutant: an analog of a transition state in enzymatic reaction.,Liu SQ, Chang T, Liu MY, LeGall J, Chang WC, Zhang JP, Liang DC, Chang WR Biochem Biophys Res Commun. 2003 Mar 14;302(3):568-74. PMID:12615072 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Nitrite reductase 3D structures

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