2e86
From Proteopedia
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| - | | | + | {{STRUCTURE_2e86| PDB=2e86 | SCENE= }} |
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'''Azide bound to copper containing nitrite reductase from A. faecalis S-6''' | '''Azide bound to copper containing nitrite reductase from A. faecalis S-6''' | ||
| + | |||
| + | ==Overview== | ||
| + | The interaction of copper-containing dissimilatory nitrite reductase from Alcaligenes faecalis S-6 ( AfNiR) with each of five small molecules was studied using crystallography and steady-state kinetics. Structural studies revealed that each small molecule interacted with the oxidized catalytic type 2 copper of AfNiR. Three small molecules (formate, acetate and nitrate) mimic the substrate by having at least two oxygen atoms for bidentate coordination to the type 2 copper atom. These three anions bound to the copper ion in the same asymmetric, bidentate manner as nitrite. Consistent with their weak inhibition of the enzyme ( K i >50 mM), the Cu-O distances in these AfNiR-inhibitor complexes were approximately 0.15 A longer than that observed in the AfNiR-nitrite complex. The binding mode of each inhibitor is determined in part by steric interactions with the side chain of active site residue Ile257. Moreover, the side chain of Asp98, a conserved residue that hydrogen bonds to type 2 copper-bound nitrite and nitric oxide, was either disordered or pointed away from the inhibitors. Acetate and formate inhibited AfNiR in a mixed fashion, consistent with the occurrence of second acetate binding site in the AfNiR-acetate complex that occludes access to the type 2 copper. A fourth small molecule, nitrous oxide, bound to the oxidized metal in a side-on fashion reminiscent of nitric oxide to the reduced copper. Nevertheless, nitrous oxide bound at a farther distance from the metal. The fifth small molecule, azide, inhibited the reduction of nitrite by AfNiR most strongly ( K ic = 2.0 +/- 0.1 mM). This ligand bound to the type 2 copper center end-on with a Cu-N c distance of approximately 2 A, and was the only inhibitor to form a hydrogen bond with Asp98. Overall, the data substantiate the roles of Asp98 and Ile257 in discriminating substrate from other small anions. | ||
==About this Structure== | ==About this Structure== | ||
2E86 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Alcaligenes_faecalis Alcaligenes faecalis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2E86 OCA]. | 2E86 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Alcaligenes_faecalis Alcaligenes faecalis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2E86 OCA]. | ||
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| + | ==Reference== | ||
| + | Conserved Active Site Residues Limit Inhibition of a Copper-Containing Nitrite Reductase by Small Molecules., Tocheva EI, Eltis LD, Murphy ME, Biochemistry. 2008 Mar 22;. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/18358002 18358002] | ||
[[Category: Alcaligenes faecalis]] | [[Category: Alcaligenes faecalis]] | ||
| - | [[Category: Nitrite reductase (NO-forming)]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Murphy, M E.P.]] | [[Category: Murphy, M E.P.]] | ||
[[Category: Tocheva, E I.]] | [[Category: Tocheva, E I.]] | ||
| - | [[Category: | + | [[Category: Azide]] |
| - | [[Category: | + | [[Category: Copper]] |
| - | [[Category: | + | [[Category: Inhibitor]] |
| - | [[Category: | + | [[Category: Kinetic study]] |
| - | [[Category: | + | [[Category: Nitrite reductase]] |
| - | [[Category: | + | [[Category: Oxidoreductase]] |
| - | [[Category: | + | [[Category: X-ray crystallography]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Apr 16 23:06:11 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 20:06, 16 April 2008
Azide bound to copper containing nitrite reductase from A. faecalis S-6
Overview
The interaction of copper-containing dissimilatory nitrite reductase from Alcaligenes faecalis S-6 ( AfNiR) with each of five small molecules was studied using crystallography and steady-state kinetics. Structural studies revealed that each small molecule interacted with the oxidized catalytic type 2 copper of AfNiR. Three small molecules (formate, acetate and nitrate) mimic the substrate by having at least two oxygen atoms for bidentate coordination to the type 2 copper atom. These three anions bound to the copper ion in the same asymmetric, bidentate manner as nitrite. Consistent with their weak inhibition of the enzyme ( K i >50 mM), the Cu-O distances in these AfNiR-inhibitor complexes were approximately 0.15 A longer than that observed in the AfNiR-nitrite complex. The binding mode of each inhibitor is determined in part by steric interactions with the side chain of active site residue Ile257. Moreover, the side chain of Asp98, a conserved residue that hydrogen bonds to type 2 copper-bound nitrite and nitric oxide, was either disordered or pointed away from the inhibitors. Acetate and formate inhibited AfNiR in a mixed fashion, consistent with the occurrence of second acetate binding site in the AfNiR-acetate complex that occludes access to the type 2 copper. A fourth small molecule, nitrous oxide, bound to the oxidized metal in a side-on fashion reminiscent of nitric oxide to the reduced copper. Nevertheless, nitrous oxide bound at a farther distance from the metal. The fifth small molecule, azide, inhibited the reduction of nitrite by AfNiR most strongly ( K ic = 2.0 +/- 0.1 mM). This ligand bound to the type 2 copper center end-on with a Cu-N c distance of approximately 2 A, and was the only inhibitor to form a hydrogen bond with Asp98. Overall, the data substantiate the roles of Asp98 and Ile257 in discriminating substrate from other small anions.
About this Structure
2E86 is a Single protein structure of sequence from Alcaligenes faecalis. Full crystallographic information is available from OCA.
Reference
Conserved Active Site Residues Limit Inhibition of a Copper-Containing Nitrite Reductase by Small Molecules., Tocheva EI, Eltis LD, Murphy ME, Biochemistry. 2008 Mar 22;. PMID:18358002 Page seeded by OCA on Wed Apr 16 23:06:11 2008
