1cce
From Proteopedia
(New page: 200px<br /><applet load="1cce" size="450" color="white" frame="true" align="right" spinBox="true" caption="1cce, resolution 2.3Å" /> '''CONSTRUCTION OF A BIS...) |
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| - | [[Image:1cce.jpg|left|200px]]<br /><applet load="1cce" size=" | + | [[Image:1cce.jpg|left|200px]]<br /><applet load="1cce" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1cce, resolution 2.3Å" /> | caption="1cce, resolution 2.3Å" /> | ||
'''CONSTRUCTION OF A BIS-AQUO HEME ENZYME AND REPLACEMENT WITH EXOGENOUS LIGAND'''<br /> | '''CONSTRUCTION OF A BIS-AQUO HEME ENZYME AND REPLACEMENT WITH EXOGENOUS LIGAND'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The crystal structure of the His-175-->Gly (H175G) mutant of cytochrome-c | + | The crystal structure of the His-175-->Gly (H175G) mutant of cytochrome-c peroxidase (EC 1.11.1.5), missing its only heme ligand, reveals that the histidine is replaced by solvent to give a bisaquo heme protein. This protein retains some residual activity, which can be stimulated or inhibited by addition of exogenous ligands. Structural analysis confirms the binding of imidazole to the heme at the position of the wild-type histidine ligand. This imidazole complex reacts readily with hydrogen peroxide to produce a radical species with novel properties. However, reactivation in this complex is incomplete (approximately 5%), which, in view of the very similar structures of the wild-type and the H175G/imidazole forms, implies a critical role for tethering of the axial ligand in catalysis. This study demonstrates the feasibility of constructing heme enzymes with no covalent link to the protein and with unnatural ligand replacements. Such enzymes may prove useful in studies of electron transfer mechanisms and in the engineering of novel heme-based catalysts. |
==About this Structure== | ==About this Structure== | ||
| - | 1CCE is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with HEM as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Cytochrome-c_peroxidase Cytochrome-c peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.5 1.11.1.5] Full crystallographic information is available from [http:// | + | 1CCE is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Cytochrome-c_peroxidase Cytochrome-c peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.5 1.11.1.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CCE OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Saccharomyces cerevisiae]] | [[Category: Saccharomyces cerevisiae]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Fitzgerald, M | + | [[Category: Fitzgerald, M M.]] |
| - | [[Category: Goodin, D | + | [[Category: Goodin, D B.]] |
| - | [[Category: Jensen, G | + | [[Category: Jensen, G M.]] |
| - | [[Category: Mcree, D | + | [[Category: Mcree, D E.]] |
| - | [[Category: Siegel, H | + | [[Category: Siegel, H A.]] |
[[Category: HEM]] | [[Category: HEM]] | ||
[[Category: oxidoreductase(h2o2(a))]] | [[Category: oxidoreductase(h2o2(a))]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:04:40 2008'' |
Revision as of 10:04, 21 February 2008
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CONSTRUCTION OF A BIS-AQUO HEME ENZYME AND REPLACEMENT WITH EXOGENOUS LIGAND
Overview
The crystal structure of the His-175-->Gly (H175G) mutant of cytochrome-c peroxidase (EC 1.11.1.5), missing its only heme ligand, reveals that the histidine is replaced by solvent to give a bisaquo heme protein. This protein retains some residual activity, which can be stimulated or inhibited by addition of exogenous ligands. Structural analysis confirms the binding of imidazole to the heme at the position of the wild-type histidine ligand. This imidazole complex reacts readily with hydrogen peroxide to produce a radical species with novel properties. However, reactivation in this complex is incomplete (approximately 5%), which, in view of the very similar structures of the wild-type and the H175G/imidazole forms, implies a critical role for tethering of the axial ligand in catalysis. This study demonstrates the feasibility of constructing heme enzymes with no covalent link to the protein and with unnatural ligand replacements. Such enzymes may prove useful in studies of electron transfer mechanisms and in the engineering of novel heme-based catalysts.
About this Structure
1CCE is a Single protein structure of sequence from Saccharomyces cerevisiae with as ligand. Active as Cytochrome-c peroxidase, with EC number 1.11.1.5 Full crystallographic information is available from OCA.
Reference
Construction of a bisaquo heme enzyme and binding by exogenous ligands., McRee DE, Jensen GM, Fitzgerald MM, Siegel HA, Goodin DB, Proc Natl Acad Sci U S A. 1994 Dec 20;91(26):12847-51. PMID:7809133
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