1npj

Crystal structure of H145A mutant of nitrite reductase from Alcaligenes faecalis

spinqualitylabelsall models 1npj, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1npj is a 3 chain structure with sequence from Alcfa. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CU Gene: NIRK OR NIR (ALCFA) Activity: Nitrite reductase (NO-forming), with EC number 1.7.2.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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 Variants of the copper-containing nitrite reductase (NiR) of Alcaligenes faecalis S6 were constructed by site-directed mutagenesis, by which the C-terminal histidine ligand (His145) of the Cu in the type-1 site was replaced by an alanine or a glycine. The type-1 sites in the NiR variants as isolated, are in the reduced form, but can be oxidized in the presence of external ligands, like (substituted) imidazoles and chloride. The reduction potential of the type-1 site of NiR-H145A reconstituted with imidazole amounts to 505 mV vs NHE (20 degrees C, pH 7, 10 mM imidazole), while for the native type-1 site it amounts to 260 mV. XRD data on crystals of the reduced and oxidized NiR-H145A variant show that in the reduced type-1 site the metal is 3-coordinated, but in the oxidized form takes up a ligand from the solution. With the fourth (exogenous) ligand in place the type-1 site is able to accept electrons at about the same rate as the wt NiR, but it is unable to pass the electron onto the type-2 site, leading to loss of enzymatic activity. It is argued that the uptake of an electron by the mutated type-1 site is accompanied by a loss of the exogenous ligand and a concomitant rise of the redox potential. This rise effectively traps the electron in the type-1 site. Reconstitution of the type-1 active site of the H145G/A variants of nitrite reductase by ligand insertion.,Wijma HJ, Boulanger MJ, Molon A, Fittipaldi M, Huber M, Murphy ME, Verbeet MP, Canters GW Biochemistry. 2003 Apr 15;42(14):4075-83. PMID:12680761 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Nitrite reductase 3D structures

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