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| [[Image:3ccx.jpg|left|200px]]
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| <!-- | | ==ALTERING SUBSTRATE SPECIFICITY AT THE HEME EDGE OF CYTOCHROME C PEROXIDASE== |
| The line below this paragraph, containing "STRUCTURE_3ccx", creates the "Structure Box" on the page.
| | <StructureSection load='3ccx' size='340' side='right'caption='[[3ccx]], [[Resolution|resolution]] 2.30Å' 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'>[[3ccx]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3CCX OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3CCX 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]] 2.3Å</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></td></tr> |
| {{STRUCTURE_3ccx| PDB=3ccx | SCENE= }}
| | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3ccx FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ccx OCA], [https://pdbe.org/3ccx PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3ccx RCSB], [https://www.ebi.ac.uk/pdbsum/3ccx PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3ccx ProSAT]</span></td></tr> |
| | </table> |
| | == Function == |
| | [https://www.uniprot.org/uniprot/CCPR_YEAST CCPR_YEAST] Destroys radicals which are normally produced within the cells and which are toxic to biological systems. |
| | == 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/cc/3ccx_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=3ccx ConSurf]. |
| | <div style="clear:both"></div> |
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| '''ALTERING SUBSTRATE SPECIFICITY AT THE HEME EDGE OF CYTOCHROME C PEROXIDASE'''
| | ==See Also== |
| | | *[[Cytochrome c peroxidase 3D structures|Cytochrome c peroxidase 3D structures]] |
| | | __TOC__ |
| ==Overview== | | </StructureSection> |
| Two mutants of cytochrome c peroxidase (CCP) are reported which exhibit unique specificities toward oxidation of small substrates. Ala-147 in CCP is located near the delta-meso edge of the heme and along the solvent access channel through which H2O2 is thought to approach the active site. This residue was replaced with Met and Tyr to investigate the hypothesis that small molecule substrates are oxidized at the exposed delta-meso edge of the heme. X-ray crystallographic analyses confirm that the side chains of A147M and A147Y are positioned over the delta-meso heme position and might therefore modify small molecule access to the oxidized heme cofactor. Steady-state kinetic measurements show that cytochrome c oxidation is enhanced 3-fold for A147Y relative to wild type, while small molecule oxidation is altered to varying degrees depending on the substrate and mutant. For example, oxidation of phenols by A147Y is reduced to less than 20% relative to the wild-type enzyme, while Vmax/e for oxidation of other small molecules is less affected by either mutation. However, the "specificity" of aniline oxidation by A147M, i.e., (Vmax/e)/Km, is 43-fold higher than in wild-type enzyme, suggesting that a specific interaction for aniline has been introduced by the mutation. Stopped-flow kinetic data show that the restricted heme access in A147Y or A147M slows the reaction between the enzyme and H202, but not to an extent that it becomes rate limiting for the oxidation of the substrates examined. The rate constant for compound ES formation with A147Y is 2.5 times slower than wild-type CCP. These observations strongly support the suggestion that small molecule oxidations occur at sites on the enzyme distinct from those utilized by cytochrome c and that the specificity of small molecule oxidation can be significantly modulated by manipulating access to the heme edge. The results help to define the role of alternative electron transfer pathways in cytochrome c peroxidase and may have useful applications in improving the specificity of peroxidase with engineered function.
| | [[Category: Large Structures]] |
| | |
| ==About this Structure==
| |
| 3CCX is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3CCX OCA].
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| ==Reference==
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| Altering substrate specificity at the heme edge of cytochrome c peroxidase., Wilcox SK, Jensen GM, Fitzgerald MM, McRee DE, Goodin DB, Biochemistry. 1996 Apr 16;35(15):4858-66. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8664277 8664277]
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| [[Category: Cytochrome-c peroxidase]] | |
| [[Category: Saccharomyces cerevisiae]] | | [[Category: Saccharomyces cerevisiae]] |
| [[Category: Single protein]]
| | [[Category: Fitzgerald MM]] |
| [[Category: Fitzgerald, M M.]] | | [[Category: Goodin DB]] |
| [[Category: Goodin, D B.]] | | [[Category: Jensen GM]] |
| [[Category: Jensen, G M.]] | | [[Category: Mcree DE]] |
| [[Category: Mcree, D E.]] | | [[Category: Wilcox SK]] |
| [[Category: Wilcox, S K.]] | |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 21:35:41 2008''
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