1zo8
From Proteopedia
(New page: 200px<br /><applet load="1zo8" size="350" color="white" frame="true" align="right" spinBox="true" caption="1zo8, resolution 1.90Å" /> '''X-ray Structure of t...) |
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==Overview== | ==Overview== | ||
| - | Halo alcohol dehalogenase HheC catalyzes the highly enantioselective | + | Halo alcohol dehalogenase HheC catalyzes the highly enantioselective dehalogenation of vicinal halo alcohols to epoxides, as well as the reverse reaction, the enantioselective and beta-regioselective nucleophilic ring opening of epoxides by pseudo-halides such as azide and cyanide. To investigate this latter reaction, we determined X-ray structures of complexes of HheC with the favored and unfavored enantiomers of para-nitrostyrene oxide. The aromatic parts of the two enantiomers bind in a very similar way, but the epoxide ring of the unfavored (S)-enantiomer binds in a nonproductive inverted manner, with the epoxide oxygen and Cbeta atom positions interchanged with respect to those of the favored (R)-enantiomer. The calculated difference in relative Gibbs binding energy is in agreement with the observed loss of a single hydrogen bond in the S bound state with respect to the R bound state. Our results indicate that it is the nonproductive binding of the unfavored (S)-enantiomer, rather than the difference in affinity for the two enantiomers, that allows HheC to catalyze the azide-mediated ring opening of para-nitrostyrene oxide with high enantioselectivity. This work represents a rare opportunity to explain the enantioselectivity of an enzymatic reaction by comparison of crystallographic data on the binding of both the favored and unfavored enantiomers. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Agrobacterium tumefaciens]] | [[Category: Agrobacterium tumefaciens]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Dijkstra, B | + | [[Category: Dijkstra, B W.]] |
| - | [[Category: Janssen, D | + | [[Category: Janssen, D B.]] |
| - | [[Category: Jong, R | + | [[Category: Jong, R M.de.]] |
[[Category: Tang, L.]] | [[Category: Tang, L.]] | ||
| - | [[Category: Tiesinga, J | + | [[Category: Tiesinga, J J.W.]] |
[[Category: Villa, A.]] | [[Category: Villa, A.]] | ||
[[Category: SNO]] | [[Category: SNO]] | ||
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[[Category: short-chain dehydrogenase/reductase]] | [[Category: short-chain dehydrogenase/reductase]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:17:29 2008'' |
Revision as of 14:17, 21 February 2008
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X-ray Structure of the haloalcohol dehalogenase HheC of Agrobacterium radiobacter AD1 in complex with (S)-para-nitrostyrene oxide, with a water molecule in the halide-binding site
Overview
Halo alcohol dehalogenase HheC catalyzes the highly enantioselective dehalogenation of vicinal halo alcohols to epoxides, as well as the reverse reaction, the enantioselective and beta-regioselective nucleophilic ring opening of epoxides by pseudo-halides such as azide and cyanide. To investigate this latter reaction, we determined X-ray structures of complexes of HheC with the favored and unfavored enantiomers of para-nitrostyrene oxide. The aromatic parts of the two enantiomers bind in a very similar way, but the epoxide ring of the unfavored (S)-enantiomer binds in a nonproductive inverted manner, with the epoxide oxygen and Cbeta atom positions interchanged with respect to those of the favored (R)-enantiomer. The calculated difference in relative Gibbs binding energy is in agreement with the observed loss of a single hydrogen bond in the S bound state with respect to the R bound state. Our results indicate that it is the nonproductive binding of the unfavored (S)-enantiomer, rather than the difference in affinity for the two enantiomers, that allows HheC to catalyze the azide-mediated ring opening of para-nitrostyrene oxide with high enantioselectivity. This work represents a rare opportunity to explain the enantioselectivity of an enzymatic reaction by comparison of crystallographic data on the binding of both the favored and unfavored enantiomers.
About this Structure
1ZO8 is a Single protein structure of sequence from Agrobacterium tumefaciens with as ligand. Full crystallographic information is available from OCA.
Reference
Structural basis for the enantioselectivity of an epoxide ring opening reaction catalyzed by halo alcohol dehalogenase HheC., de Jong RM, Tiesinga JJ, Villa A, Tang L, Janssen DB, Dijkstra BW, J Am Chem Soc. 2005 Sep 28;127(38):13338-43. PMID:16173767
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