View source for 5azr


==Crystal structure of aqua-cobalt(III) tetradehydrocorrin in the heme pocket of horse heart myoglobin==
<StructureSection load='5azr' size='340' side='right'caption='[[5azr]], [[Resolution|resolution]] 1.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5azr]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Equus_caballus Equus caballus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5AZR OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5AZR FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.2&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=5azr FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5azr OCA], [https://pdbe.org/5azr PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5azr RCSB], [https://www.ebi.ac.uk/pdbsum/5azr PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5azr ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/MYG_HORSE MYG_HORSE] Serves as a reserve supply of oxygen and facilitates the movement of oxygen within muscles.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Myoglobins reconstituted with aqua- and cyano-Co(III) tetradehydrocorrins, rMb(Co(III)(OH2)(TDHC)) and rMb(Co(III)(CN)(TDHC)), respectively, were prepared and investigated as models of a cobalamin-dependent enzyme. The former protein was obtained by oxidation of rMb(Co(II)(TDHC)) with K3[Fe(CN)6]. The cyanide-coordinated Co(III) species in the latter protein was prepared by ligand exchange of rMb(Co(III)(OH2)(TDHC)) with exogenous cyanide upon addition of KCN. The X-ray crystallographic study reveals the hexacoordinated structures of rMb(Co(III)(OH)(TDHC)) and rMb(Co(III)(CN)(TDHC)) at 1.20 and 1.40 A resolution, respectively. The (13)C NMR chemical shifts of the cyanide in rMb(Co(III)(CN)(TDHC)) were determined to be 108.6 and 110.6 ppm. IR measurements show that the cyanide of rMb(Co(III)(CN)(TDHC)) has a stretching frequency peak at 2151 cm(-1) which is higher than that of cyanocobalamin. The (13)C NMR and IR measurements indicate weaker coordination of the cyanide to Co(III)(TDHC) relative to cobalamin, a vitamin B12 derivative. Thus, the extent of pi-back-donation from the cobalt ion to the cyanide ion is lower in rMb(Co(III)(CN)(TDHC)). Furthermore, the pK1/2 values of rMb(Co(III)(OH2)(TDHC)) and rMb(Co(III)(CN)(TDHC)) were determined by a pH titration experiment to be 3.2 and 5.5, respectively, indicating that the cyanide ligation weakens the Co-N(His93) bond. Theoretical calculations also demonstrate that the axial ligand exchange from water to cyanide elongates the Co-N(axial) bond with a decrease in the bond dissociation energy. Taken together, the cyano-Co(III) tetradehydrocorrin in myoglobin is appropriate for investigation as a structural analogue of methylcobalamin, a key intermediate in methionine synthase reaction.

Crystal Structures and Coordination Behavior of Aqua- and Cyano-Co(III) Tetradehydrocorrins in the Heme Pocket of Myoglobin.,Morita Y, Oohora K, Mizohata E, Sawada A, Kamachi T, Yoshizawa K, Inoue T, Hayashi T Inorg Chem. 2016 Feb 1;55(3):1287-95. doi: 10.1021/acs.inorgchem.5b02598. Epub, 2016 Jan 13. PMID:26760442<ref>PMID:26760442</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5azr" style="background-color:#fffaf0;"></div>

==See Also==
*[[Myoglobin 3D structures|Myoglobin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Equus caballus]]
[[Category: Large Structures]]
[[Category: Hayashi T]]
[[Category: Inoue T]]
[[Category: Mizohata E]]
[[Category: Morita Y]]
[[Category: Oohora K]]