1q8j
From Proteopedia
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'''Cobalamin-dependent methionine synthase (1-566) from Thermotoga maritima (Cd2+, Hcy, methyltetrahydrofolate complex)''' | '''Cobalamin-dependent methionine synthase (1-566) from Thermotoga maritima (Cd2+, Hcy, methyltetrahydrofolate complex)''' | ||
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[[Category: Matthews, R G.]] | [[Category: Matthews, R G.]] | ||
[[Category: Romanchuk, G.]] | [[Category: Romanchuk, G.]] | ||
| - | [[Category: | + | [[Category: Cobalamin]] |
| - | [[Category: | + | [[Category: Folate]] |
| - | [[Category: | + | [[Category: Homocysteine]] |
| - | [[Category: | + | [[Category: Methionine]] |
| - | [[Category: | + | [[Category: Vitamin b12]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:59:50 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 02:59, 3 May 2008
Cobalamin-dependent methionine synthase (1-566) from Thermotoga maritima (Cd2+, Hcy, methyltetrahydrofolate complex)
Overview
B(12)-dependent methionine synthase (MetH) is a large modular enzyme that utilizes the cobalamin cofactor as a methyl donor or acceptor in three separate reactions. Each methyl transfer occurs at a different substrate-binding domain and requires a different arrangement of modules. In the catalytic cycle, the cobalamin-binding domain carries methylcobalamin to the homocysteine (Hcy) domain to form methionine and returns cob(I)alamin to the folate (Fol) domain for remethylation by methyltetrahydrofolate (CH(3)-H(4)folate). Here, we describe crystal structures of a fragment of MetH from Thermotoga maritima comprising the domains that bind Hcy and CH(3)-H(4)folate. These substrate-binding domains are (beta alpha)(8) barrels packed tightly against one another with their barrel axes perpendicular. The properties of the domain interface suggest that the two barrels remain associated during catalysis. The Hcy and CH(3)-H(4)folate substrates are bound at the C termini of their respective barrels in orientations that position them for reaction with cobalamin, but the two active sites are separated by approximately 50 A. To complete the catalytic cycle, the cobalamin-binding domain must travel back and forth between these distant active sites.
About this Structure
1Q8J is a Single protein structure of sequence from Thermotoga maritima. Full crystallographic information is available from OCA.
Reference
Structures of the N-terminal modules imply large domain motions during catalysis by methionine synthase., Evans JC, Huddler DP, Hilgers MT, Romanchuk G, Matthews RG, Ludwig ML, Proc Natl Acad Sci U S A. 2004 Mar 16;101(11):3729-36. Epub 2004 Jan 29. PMID:14752199 Page seeded by OCA on Sat May 3 05:59:50 2008
