1req
From Proteopedia
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'''METHYLMALONYL-COA MUTASE''' | '''METHYLMALONYL-COA MUTASE''' | ||
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[[Category: Evans, P R.]] | [[Category: Evans, P R.]] | ||
[[Category: Mancia, F.]] | [[Category: Mancia, F.]] | ||
| - | [[Category: | + | [[Category: Intramolecular transferase]] |
| - | [[Category: | + | [[Category: Isomerase]] |
| - | [[Category: | + | [[Category: Mutase]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 07:24:19 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 04:24, 3 May 2008
METHYLMALONYL-COA MUTASE
Overview
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.
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 Sat May 3 07:24:19 2008
