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1mno

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[[Image:1mno.jpg|left|200px]]<br /><applet load="1mno" size="350" color="white" frame="true" align="right" spinBox="true"
 
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caption="1mno, resolution 1.95&Aring;" />
 
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'''V68N MYOGLOBIN OXY FORM'''<br />
 
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==Overview==
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==V68N MYOGLOBIN OXY FORM==
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The isopropyl side chain of valine68 in myoglobin has been replaced by the acetamide side chain of asparagine in an attempt to engineer higher oxygen affinity. The asparagine replacement introduces a second hydrogen bond donor group into the distal heme pocket which could further stabilize bound oxygen. The Val68 to Asn substitution leads to approximately 3-fold increases in oxygen affinity and 4-6-fold decreases in CO affinity. As a result, the M-value (KCO/KO2) is lowered 15-20-fold to a value close to unity. An even larger enhancement of O2 affinity is seen when asparagine68 is inserted into H64L sperm whale myoglobin which lacks a distal histidine. The overall rate constants for oxygen and carbon monoxide binding to the single V68N myoglobin mutants are uniformly lower than those for the wild-type protein. In contrast, the overall rate constant for NO association is unchanged. Analyses of time courses monitoring the geminate recombination of ligands following nanosecond and picosecond flash photolysis of MbNO and MbO2 indicate that the barrier to ligand binding from within the heme pocket has been raised with little effect on the barrier to diffusion of the ligand into the pocket from the solvent. The crystal structures of the aquomet, deoxy, oxy, and carbon monoxy forms of the V68N mutant have been determined to resolutions ranging from 1.75 to 2.2 A at 150 K. The overall structures are very similar to those of the wild-type protein with the principal alterations taking place within and around the distal heme pocket. In all four structures the asparagine68 side chain lies almost parallel to the plane of the heme with its amide group directed toward the back of the distal heme pocket. The coordinated water molecule in the aquomet form and the bound oxygen in the oxy form can form hydrogen-bonding interactions with both the Asn68 amide group and the imidazole side chain of His64. Surprisingly, in the carbon monoxy form of the V68N mutant, the histidine64 side chain has swung completely out the distal pocket, its place being taken by two ordered water molecules. Overall, these functional and structural results show that the asparagine68 side chain (i) forms a strong hydrogen bond with bound oxygen through its -NH2 group but (ii) sterically hinders the approach of ligands to the iron from within the distal heme pocket.
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<StructureSection load='1mno' size='340' side='right'caption='[[1mno]], [[Resolution|resolution]] 1.95&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1mno]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MNO OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1MNO FirstGlance]. <br>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.95&#8491;</td></tr>
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<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene>, <scene name='pdbligand=OXY:OXYGEN+MOLECULE'>OXY</scene></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1mno FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1mno OCA], [https://pdbe.org/1mno PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1mno RCSB], [https://www.ebi.ac.uk/pdbsum/1mno PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1mno ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/MYG_PIG MYG_PIG] Serves as a reserve supply of oxygen and facilitates the movement of oxygen within muscles.
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/mn/1mno_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1mno ConSurf].
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<div style="clear:both"></div>
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==About this Structure==
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==See Also==
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1MNO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa] with <scene name='pdbligand=HEM:'>HEM</scene> and <scene name='pdbligand=OXY:'>OXY</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MNO OCA].
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*[[Myoglobin 3D structures|Myoglobin 3D structures]]
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__TOC__
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==Reference==
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</StructureSection>
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Stabilizing bound O2 in myoglobin by valine68 (E11) to asparagine substitution., Krzywda S, Murshudov GN, Brzozowski AM, Jaskolski M, Scott EE, Klizas SA, Gibson QH, Olson JS, Wilkinson AJ, Biochemistry. 1998 Nov 10;37(45):15896-907. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=9843395 9843395]
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[[Category: Large Structures]]
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[[Category: Single protein]]
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[[Category: Sus scrofa]]
[[Category: Sus scrofa]]
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[[Category: Brzozowski, A M.]]
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[[Category: Brzozowski AM]]
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[[Category: Gibson, Q H.]]
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[[Category: Gibson QH]]
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[[Category: Jaskolski, M.]]
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[[Category: Jaskolski M]]
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[[Category: Klizas, S A.]]
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[[Category: Klizas SA]]
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[[Category: Krzywda, S.]]
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[[Category: Krzywda S]]
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[[Category: Murshudov, G N.]]
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[[Category: Murshudov GN]]
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[[Category: Olson, J S.]]
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[[Category: Olson JS]]
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[[Category: Scott, E E.]]
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[[Category: Scott EE]]
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[[Category: Wilkinson, A J.]]
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[[Category: Wilkinson AJ]]
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[[Category: HEM]]
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[[Category: OXY]]
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[[Category: myoglobin]]
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[[Category: oxy]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:57:06 2008''
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Current revision

V68N MYOGLOBIN OXY FORM

PDB ID 1mno

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