1eex
From Proteopedia
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'''CRYSTAL STRUCTURE OF THE DIOL DEHYDRATASE-ADENINYLPENTYLCOBALAMIN COMPLEX FROM KLEBSIELLA OXYTOCA''' | '''CRYSTAL STRUCTURE OF THE DIOL DEHYDRATASE-ADENINYLPENTYLCOBALAMIN COMPLEX FROM KLEBSIELLA OXYTOCA''' | ||
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[[Category: Toraya, T.]] | [[Category: Toraya, T.]] | ||
[[Category: Yasuoka, N.]] | [[Category: Yasuoka, N.]] | ||
| - | [[Category: | + | [[Category: Coenzyme b12]] |
| - | [[Category: | + | [[Category: Potassium ion]] |
| - | [[Category: | + | [[Category: Propanediol]] |
| - | [[Category: | + | [[Category: Tim barrel]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 15:00:43 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 12:00, 2 May 2008
CRYSTAL STRUCTURE OF THE DIOL DEHYDRATASE-ADENINYLPENTYLCOBALAMIN COMPLEX FROM KLEBSIELLA OXYTOCA
Overview
BACKGROUND: Adenosylcobalamin (coenzyme B(12)) serves as a cofactor for enzymatic radical reactions. The adenosyl radical, a catalytic radical in these reactions, is formed by homolysis of the cobalt-carbon bond of the coenzyme, although the mechanism of cleavage of its organometallic bond remains unsolved. RESULTS: We determined the three-dimensional structures of diol dehydratase complexed with adeninylpentylcobalamin and with cyanocobalamin at 1.7 A and 1.9 A resolution, respectively, at cryogenic temperatures. In the adeninylpentylcobalamin complex, the adenine ring is bound parallel to the corrin ring as in the free form and methylmalonyl-CoA-mutase-bound coenzyme, but with the other side facing pyrrole ring C. All of its nitrogen atoms except for N(9) are hydrogen-bonded to mainchain amide oxygen and amide nitrogen atoms, a sidechain hydroxyl group, and a water molecule. As compared with the cyanocobalamin complex, the sidechain of Seralpha224 rotates by 120 degrees to hydrogen bond with N(3) of the adenine ring. CONCLUSIONS: The structure of the adenine-ring-binding site provides a molecular basis for the strict specificity of diol dehydratase for the coenzyme adenosyl group. The superimposition of the structure of the free coenzyme on that of enzyme-bound adeninylpentylcobalamin demonstrated that the tight enzyme-coenzyme interactions at both the cobalamin moiety and adenine ring of the adenosyl group would inevitably lead to cleavage of the cobalt-carbon bond. Rotation of the ribose moiety around the glycosidic linkage makes the 5'-carbon radical accessible to the hydrogen atom of the substrate to be abstracted.
About this Structure
1EEX is a Protein complex structure of sequences from Klebsiella oxytoca. Full crystallographic information is available from OCA.
Reference
How a protein generates a catalytic radical from coenzyme B(12): X-ray structure of a diol-dehydratase-adeninylpentylcobalamin complex., Masuda J, Shibata N, Morimoto Y, Toraya T, Yasuoka N, Structure. 2000 Jul 15;8(7):775-88. PMID:10903944 Page seeded by OCA on Fri May 2 15:00:43 2008
