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| - | [[Image:2spm.gif|left|200px]] | |
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| - | <!-- | + | ==A NOVEL SITE-DIRECTED MUTANT OF MYOGLOBIN WITH AN UNUSUALLY HIGH O2 AFFINITY AND LOW AUTOOXIDATION RATE== |
| - | The line below this paragraph, containing "STRUCTURE_2spm", creates the "Structure Box" on the page.
| + | <StructureSection load='2spm' size='340' side='right'caption='[[2spm]], [[Resolution|resolution]] 1.70Å' scene=''> |
| - | You may change the PDB parameter (which sets the PDB file loaded into the applet)
| + | == Structural highlights == |
| - | or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
| + | <table><tr><td colspan='2'>[[2spm]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Physeter_catodon Physeter catodon]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2SPM OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2SPM FirstGlance]. <br> |
| - | or leave the SCENE parameter empty for the default display.
| + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.7Å</td></tr> |
| - | -->
| + | <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=SO4:SULFATE+ION'>SO4</scene></td></tr> |
| - | {{STRUCTURE_2spm| PDB=2spm | SCENE= }}
| + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2spm FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2spm OCA], [https://pdbe.org/2spm PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2spm RCSB], [https://www.ebi.ac.uk/pdbsum/2spm PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2spm ProSAT]</span></td></tr> |
| | + | </table> |
| | + | == Function == |
| | + | [https://www.uniprot.org/uniprot/MYG_PHYMC MYG_PHYMC] Serves as a reserve supply of oxygen and facilitates the movement of oxygen within muscles. |
| | + | == Evolutionary Conservation == |
| | + | [[Image:Consurf_key_small.gif|200px|right]] |
| | + | Check<jmol> |
| | + | <jmolCheckbox> |
| | + | <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/sp/2spm_consurf.spt"</scriptWhenChecked> |
| | + | <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked> |
| | + | <text>to colour the structure by Evolutionary Conservation</text> |
| | + | </jmolCheckbox> |
| | + | </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=2spm ConSurf]. |
| | + | <div style="clear:both"></div> |
| | | | |
| - | '''A NOVEL SITE-DIRECTED MUTANT OF MYOGLOBIN WITH AN UNUSUALLY HIGH O2 AFFINITY AND LOW AUTOOXIDATION RATE'''
| + | ==See Also== |
| - | | + | *[[Myoglobin 3D structures|Myoglobin 3D structures]] |
| - | | + | __TOC__ |
| - | ==Overview== | + | </StructureSection> |
| - | Mutants of sperm whale myoglobin were constructed at position 29 (B10 in helix notation) to examine the effects of distal pocket size on the rates of ligand binding and autooxidation. Leu29 was replaced with Ala, Val, and Phe using the synthetic gene and Escherichia coli expression system of Springer and Sligar (Springer, B. A., and Sligar, S. G. (1987) Proc. Natl. Acad. Sci. U. S. A. 84, 8961-8965). Structures of the ferric forms of Val29 and Phe29, and the oxy form of Phe29 myoglobin were determined to 1.7 A by x-ray crystallography. The ferric mutant proteins are remarkably isomorphous with the wild type protein except in the immediate vicinity of residue 29. Thus, the protein structure in the distal pocket of myoglobin can accommodate either a large "hole" (i.e. Ala or Val) or a large side chain (i.e. Phe) at position 29 without perturbation of tertiary structure. Phe29 oxymyoglobin is also identical to the native oxy protein in terms of overall structure and interactions between the bound O2 and His64, Val68, Phe43, and Ile107. The distance between the nearest side chain atom of residue 29 and the second atom of the bound oxygen molecule is 3.2 A in the Phe29 protein and 4.9 A in native myoglobin. The equilibrium constants for O2 binding to Ala29, Val29, and Leu29 (native) myoglobin are the same, approximately 1.0 x 10(6) M-1 at 20 degrees C, whereas that for the Phe29 protein is markedly greater, 15 x 10(6) M-1. This increase in affinity is due primarily to a 10-fold decrease in the O2 dissociation rate constant for the Phe29 mutant and appears to be the result of stabilizing interactions between the negative portion of the bound O2 dipole and the partially positive edge of the phenyl ring. Increasing the size of residue 29 causes large decreases in the rate of autooxidation of myoglobin: k(ox) = 0.24, 0.23, 0.055, and 0.005 h-1 for Ala29, Val29, Leu29 (native), and Phe29 myoglobin, respectively, in air at 37 degrees C. Thus, the Leu29----Phe mutation produces a reduced protein that is remarkably stable and is expressed in E. coli as 100% MbO2. The selective pressure to conserve Leu29 at the B10 position probably represents a compromise between reducing the rate of autooxidation and maintaining a large enough O2 dissociation rate constant to allow rapid oxygen release during respiration.
| + | [[Category: Large Structures]] |
| - | | + | |
| - | ==About this Structure==
| + | |
| - | 2SPM is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Physeter_catodon Physeter catodon]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2SPM OCA].
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| - | | + | |
| - | ==Reference==
| + | |
| - | A novel site-directed mutant of myoglobin with an unusually high O2 affinity and low autooxidation rate., Carver TE, Brantley RE Jr, Singleton EW, Arduini RM, Quillin ML, Phillips GN Jr, Olson JS, J Biol Chem. 1992 Jul 15;267(20):14443-50. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/1629229 1629229]
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| | [[Category: Physeter catodon]] | | [[Category: Physeter catodon]] |
| - | [[Category: Single protein]]
| + | [[Category: Arduini RM]] |
| - | [[Category: Arduini, R M.]] | + | [[Category: Phillips Jr GN]] |
| - | [[Category: Jr., G N.Phillips.]] | + | [[Category: Quillin ML]] |
| - | [[Category: Quillin, M L.]] | + | |
| - | [[Category: Oxygen storage]]
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| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 17:20:53 2008''
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