2ppe

<StructureSection load='2ppe' size='340' side='right' caption='[[2ppe]], [[Resolution|resolution]] 1.75&Aring;' scene=''>

<table><tr><td colspan='2'>[[2ppe]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Alcfa Alcfa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2PPE OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2PPE FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene>, <scene name='pdbligand=CU:COPPER+(II)+ION'>CU</scene>, <scene name='pdbligand=CU1:COPPER+(I)+ION'>CU1</scene>, <scene name='pdbligand=NO:NITRIC+OXIDE'>NO</scene>, <scene name='pdbligand=TRS:2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL'>TRS</scene></td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Nitrite_reductase_(NO-forming) Nitrite reductase (NO-forming)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.7.2.1 1.7.2.1] </span></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2ppe FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ppe OCA], [http://pdbe.org/2ppe PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=2ppe RCSB], [http://www.ebi.ac.uk/pdbsum/2ppe PDBsum]</span></td></tr>

<scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/pp/2ppe_consurf.spt"</scriptWhenChecked>

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== Publication Abstract from PubMed ==

Nitrite reductase (NiR) is an enzyme that uses type 1 and type 2 copper sites to reduce nitrite to nitric oxide during bacterial denitrification. A copper-nitrosyl intermediate is a proposed, yet poorly characterized feature of the NiR catalytic cycle. This intermediate is formally described as Cu(I)-NO+ and is proposed to be formed at the type 2 copper site after nitrite binding and electron transfer from the type 1 copper site. In this study, copper-nitrosyl complexes were formed by prolonged exposure of exogenous NO to crystals of wild-type and two variant forms of NiR from Alcaligenes faecalis (AfNiR), and the structures were determined to 1.8 A or better resolution. Exposing oxidized wild-type crystals to NO results in the reverse reaction and formation of nitrite that remains bound at the active site. In a type 1 copper site mutant (H145A) that is incapable of electron transfer to the type 2 site, the reverse reaction is not observed. Instead, in both oxidized and reduced H145A crystals, NO is observed bound in a side-on manner to the type 2 copper. In AfNiR, Asp98 forms hydrogen bonds to both substrate and product bound to the type 2 Cu. In the D98N variant, NO is bound side-on but is more disordered when observed for the wild-type enzyme. The solution EPR spectra of the crystallographically characterized NiR-NO complexes indicate the presence of an oxidized type 2 copper site and thus are interpreted as resulting from stable copper-nitrosyls and formally assigned as Cu(II)-NO-. A reaction scheme in which a second NO molecule is oxidized to nitrite can account for the formation of a Cu(II)-NO- species after exposure of the oxidized H145A variant to NO gas.

Stable copper-nitrosyl formation by nitrite reductase in either oxidation state.,Tocheva EI, Rosell FI, Mauk AG, Murphy ME Biochemistry. 2007 Oct 30;46(43):12366-74. Epub 2007 Oct 9. PMID:17924665<ref>PMID:17924665</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 2ppe" style="background-color:#fffaf0;"></div>

*[[Nitric reductase|Nitric reductase]]

[[Category: Alcfa]]

[[Category: Murphy, M E.P]]

[[Category: Tocheva, E I]]

[[Category: Bacteria]]

[[Category: Oxidoreductase]]