| Isopentenyl diphosphate isomerase catalyzed reactions in D2O: product release limits the rate of this sluggish enzyme-catalyzed reaction. | |
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MedLine Citation:
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PMID: 22471428 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The E. coli isopentenyl diphosphate isomerase (IDI) catalyzed reaction of isopentenyl diphosphate (IPP) in D(2)O gives a 66% yield of dimethylallyl diphosphate labeled with deuterium at the (E)-methyl group (d-DMAPP) and a 34% yield of IPP labeled with 1 mol of deuterium at C-2 (d-IPP). This shows that the release to D(2)O of the initial product of the IDI-catalyzed reaction (d-DMAPP) is slower than its conversion to d-IPP. Product dissociation is therefore rate determining for isomerization of IPP with a rate constant k(dis) ≈ k(cat) = 0.08 s(-1). The data provide an estimated rate constant of k(as) = 6 × 10(3) M(-1) s(-1) for binding of DMAPP to E. coli IDI that is similar to rate constants determined for the binding of N-protonated 2-amino ethyl diphosphate intermediate analogs to IDI from yeast [Reardon, J. E.; Abeles, R. H. Biochemistry1986, 25, 5609-5616]. We propose that ligand binding to IDI is relatively slow because there is a significant kinetic barrier to reorganization of the initial encounter complex between enzyme, substrate, and an essential Mg(2+) to form the Michaelis complex where the metal cation bridges the protein and the substrate diphosphate group. |
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Authors:
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Venkatadurga Jonnalagadda; Krisztina Toth; John P Richard |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2012-04-05 |
Journal Detail:
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Title: Journal of the American Chemical Society Volume: 134 ISSN: 1520-5126 ISO Abbreviation: J. Am. Chem. Soc. Publication Date: 2012 Apr |
Date Detail:
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Created Date: 2012-04-18 Completed Date: 2012-09-26 Revised Date: 2013-05-20 |
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: 6568-70 Citation Subset: IM |
Copyright Information:
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© 2012 American Chemical Society |
Affiliation:
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Department of Chemistry, University at Buffalo, Buffalo, New York 14260, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Carbon-Carbon Double Bond Isomerases
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metabolism* Catalysis Deuterium Oxide* Escherichia coli / enzymology Hemiterpenes / metabolism Kinetics Organophosphorus Compounds / metabolism |
| Grant Support | |
ID/Acronym/Agency:
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GM39754/GM/NIGMS NIH HHS; R01 GM039754-23/GM/NIGMS NIH HHS; R01 GM039754-24/GM/NIGMS NIH HHS; R01 GM039754-25/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Hemiterpenes; 0/Organophosphorus Compounds; 358-71-4/isopentenyl pyrophosphate; 7789-20-0/Deuterium Oxide; EC 5.3.3.-/Carbon-Carbon Double Bond Isomerases; EC 5.3.3.2/isopentenyldiphosphate delta-isomerase |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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