1ccw
From Proteopedia
(New page: 200px<br /><applet load="1ccw" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ccw, resolution 1.60Å" /> '''STRUCTURE OF THE COE...) |
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| - | [[Image:1ccw.gif|left|200px]]<br /><applet load="1ccw" size=" | + | [[Image:1ccw.gif|left|200px]]<br /><applet load="1ccw" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ccw, resolution 1.60Å" /> | caption="1ccw, resolution 1.60Å" /> | ||
'''STRUCTURE OF THE COENZYME B12 DEPENDENT ENZYME GLUTAMATE MUTASE FROM CLOSTRIDIUM COCHLEARIUM'''<br /> | '''STRUCTURE OF THE COENZYME B12 DEPENDENT ENZYME GLUTAMATE MUTASE FROM CLOSTRIDIUM COCHLEARIUM'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Glutamate mutase (Glm) equilibrates (S)-glutamate with | + | BACKGROUND: Glutamate mutase (Glm) equilibrates (S)-glutamate with (2S,3S)-3-methylaspartate. Catalysis proceeds with the homolytic cleavage of the organometallic bond of the cofactor to yield a 5'-desoxyadenosyl radical. This radical then abstracts a hydrogen atom from the protein-bound substrate to initiate the rearrangement reaction. Glm from Clostridium cochlearium is a heterotetrameric molecule consisting of two sigma and two epsilon polypeptide chains. RESULTS: We have determined the crystal structures of inactive recombinant Glm reconstituted with either cyanocobalamin or methylcobalamin. The molecule shows close similarity to the structure of methylmalonyl CoA mutase (MCM), despite poor sequence similarity between its catalytic epsilon subunit and the corresponding TIM-barrel domain of MCM. Each of the two independent B12 cofactor molecules is associated with a substrate-binding site, which was found to be occupied by a (2S,3S)-tartrate ion. A 1:1 mixture of cofactors with cobalt in oxidation states II and III was observed in both crystal structures of inactive Glm. CONCLUSIONS: The long axial cobalt-nitrogen bond first observed in the structure of MCM appears to result from a contribution of the species without upper ligand. The tight binding of the tartrate ion conforms to the requirements of tight control of the reactive intermediates and suggests how the enzyme might use the substrate-binding energy to initiate cleavage of the cobalt-carbon bond. The cofactor does not appear to have a participating role during the radical rearrangement reaction. |
==About this Structure== | ==About this Structure== | ||
| - | 1CCW is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Clostridium_cochlearium Clostridium cochlearium] with TAR and CNC as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Methylaspartate_mutase Methylaspartate mutase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.4.99.1 5.4.99.1] Full crystallographic information is available from [http:// | + | 1CCW is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Clostridium_cochlearium Clostridium cochlearium] with <scene name='pdbligand=TAR:'>TAR</scene> and <scene name='pdbligand=CNC:'>CNC</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Methylaspartate_mutase Methylaspartate mutase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.4.99.1 5.4.99.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CCW OCA]. |
==Reference== | ==Reference== | ||
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[[Category: tim-barrel]] | [[Category: tim-barrel]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:04:46 2008'' |
Revision as of 10:04, 21 February 2008
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STRUCTURE OF THE COENZYME B12 DEPENDENT ENZYME GLUTAMATE MUTASE FROM CLOSTRIDIUM COCHLEARIUM
Overview
BACKGROUND: Glutamate mutase (Glm) equilibrates (S)-glutamate with (2S,3S)-3-methylaspartate. Catalysis proceeds with the homolytic cleavage of the organometallic bond of the cofactor to yield a 5'-desoxyadenosyl radical. This radical then abstracts a hydrogen atom from the protein-bound substrate to initiate the rearrangement reaction. Glm from Clostridium cochlearium is a heterotetrameric molecule consisting of two sigma and two epsilon polypeptide chains. RESULTS: We have determined the crystal structures of inactive recombinant Glm reconstituted with either cyanocobalamin or methylcobalamin. The molecule shows close similarity to the structure of methylmalonyl CoA mutase (MCM), despite poor sequence similarity between its catalytic epsilon subunit and the corresponding TIM-barrel domain of MCM. Each of the two independent B12 cofactor molecules is associated with a substrate-binding site, which was found to be occupied by a (2S,3S)-tartrate ion. A 1:1 mixture of cofactors with cobalt in oxidation states II and III was observed in both crystal structures of inactive Glm. CONCLUSIONS: The long axial cobalt-nitrogen bond first observed in the structure of MCM appears to result from a contribution of the species without upper ligand. The tight binding of the tartrate ion conforms to the requirements of tight control of the reactive intermediates and suggests how the enzyme might use the substrate-binding energy to initiate cleavage of the cobalt-carbon bond. The cofactor does not appear to have a participating role during the radical rearrangement reaction.
About this Structure
1CCW is a Protein complex structure of sequences from Clostridium cochlearium with and as ligands. Active as Methylaspartate mutase, with EC number 5.4.99.1 Full crystallographic information is available from OCA.
Reference
Glutamate mutase from Clostridium cochlearium: the structure of a coenzyme B12-dependent enzyme provides new mechanistic insights., Reitzer R, Gruber K, Jogl G, Wagner UG, Bothe H, Buckel W, Kratky C, Structure. 1999 Aug 15;7(8):891-902. PMID:10467146
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