| Understanding the mechanism of B(12)-dependent diol dehydratase: a synergistic retro-push--pull proposal. | |
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MedLine Citation:
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PMID: 11456766 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Ab initio molecular orbital theory is used to investigate the coenzyme B(12)-dependent reactions catalyzed by diol dehydratase. The key step in such reactions is believed to be a 1,2-hydroxyl migration, which occurs within free-radical intermediates. The barrier for this migration, if unassisted, is calculated to be too high to be consistent with the observed reaction rate. However, we find that "pushing" the migrating hydroxyl, through interaction with a suitable acid, is able to provide significant catalysis. This is denoted retro-push catalysis, the retro prefix signifying that the motion of the migrating group is in the direction opposite to the electron motion. Similarly, the "pulling" of the migrating group, through interaction of the spectator hydroxyl with an appropriate base, is found to substantially reduce the rearrangement barrier. Importantly, the combination of these two effects results in a barrier reduction that is notably greater than additive. This synergistic interplay of the push and the pull provides an attractive means of catalysis. Our proposed retro-push--pull mechanism leads to results that are consistent with isotope-labeling experiments, with experimental rate data, and with the crystal structure of the enzyme. |
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Authors:
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D M Smith; B T Golding; L Radom |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Journal of the American Chemical Society Volume: 123 ISSN: 0002-7863 ISO Abbreviation: J. Am. Chem. Soc. Publication Date: 2001 Feb |
Date Detail:
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Created Date: 2001-07-17 Completed Date: 2001-10-11 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7503056 Medline TA: J Am Chem Soc Country: United States |
Other Details:
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Languages: eng Pagination: 1664-75 Citation Subset: IM |
Affiliation:
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Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Catalysis Cobamides / chemistry, metabolism* Electron Transport Models, Chemical Propanediol Dehydratase / chemistry, metabolism* |
| Chemical | |
Reg. No./Substance:
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0/Cobamides; EC 4.2.1.28/Propanediol Dehydratase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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