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1req

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{{STRUCTURE_1req| PDB=1req | SCENE= }}
{{STRUCTURE_1req| PDB=1req | SCENE= }}
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'''METHYLMALONYL-COA MUTASE'''
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===METHYLMALONYL-COA MUTASE===
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==Overview==
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BACKGROUND. The enzyme methylmalonyl-coenzyme A (CoA) mutase, an alphabeta heterodimer of 150 kDa, is a member of a class of enzymes that uses coenzyme B12 (adenosylcobalamin) as a cofactor. The enzyme induces the formation of an adenosyl radical from the cofactor. This radical then initiates a free-radical rearrangement of its substrate, succinyl-CoA, to methylmalonyl-CoA. RESULTS. Reported here is the crystal structure at 2 A resolution of methylmalonyl-CoA mutase from Propionibacterium shermanii in complex with coenzyme B12 and with the partial substrate desulpho-CoA (lacking the succinyl group and the sulphur atom of the substrate). The coenzyme is bound by a domain which shares a similar fold to those of flavodoxin and the B12-binding domain of methylcobalamin-dependent methionine synthase. The cobalt atom is coordinated, via a long bond, to a histidine from the protein. The partial substrate is bound along the axis of a (beta/alpha)8 TIM barrel domain. CONCLUSIONS. The histidine-cobalt distance is very long (2.5 A compared with 1.95-2.2 A in free cobalamins), suggesting that the enzyme positions the histidine in order to weaken the metal-carbon bond of the cofactor and favour the formation of the initial radical species. The active site is deeply buried, and the only access to it is through a narrow tunnel along the axis of the TIM barrel domain.
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(as it appears on PubMed at http://www.pubmed.gov), where 8805541 is the PubMed ID number.
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{{ABSTRACT_PUBMED_8805541}}
==About this Structure==
==About this Structure==
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[[Category: Isomerase]]
[[Category: Isomerase]]
[[Category: Mutase]]
[[Category: Mutase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 07:24:19 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 09:56:17 2008''

Revision as of 06:56, 29 July 2008

Image:1req.png

Template:STRUCTURE 1req

METHYLMALONYL-COA MUTASE

Template:ABSTRACT PUBMED 8805541

About this Structure

1REQ is a Protein complex structure of sequences from Propionibacterium freudenreichii subsp. shermanii. Full crystallographic information is available from OCA.

Reference

How coenzyme B12 radicals are generated: the crystal structure of methylmalonyl-coenzyme A mutase at 2 A resolution., Mancia F, Keep NH, Nakagawa A, Leadlay PF, McSweeney S, Rasmussen B, Bosecke P, Diat O, Evans PR, Structure. 1996 Mar 15;4(3):339-50. PMID:8805541

Page seeded by OCA on Tue Jul 29 09:56:17 2008

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