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| [[Image:1zmt.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1zmt| PDB=1zmt | SCENE= }} | | {{STRUCTURE_1zmt| PDB=1zmt | SCENE= }} |
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| '''Structure of haloalcohol dehalogenase HheC of Agrobacterium radiobacter AD1 in complex with (R)-para-nitro styrene oxide, with a water molecule in the halide-binding site'''
| | ===Structure of haloalcohol dehalogenase HheC of Agrobacterium radiobacter AD1 in complex with (R)-para-nitro styrene oxide, with a water molecule in the halide-binding site=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_16173767}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16173767 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16173767}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Haloalcohol dehalogenase]] | | [[Category: Haloalcohol dehalogenase]] |
| [[Category: Halohydrin dehalogenase]] | | [[Category: Halohydrin dehalogenase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 17:49:17 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 20:33:15 2008'' |
