Propene Activation by the Oxo-Iron Active Species of Taurine/α-Ketoglutarate Dioxygenase (TauD) Enzyme. How Does the Catalysis Compare to Heme-Enzymes?
Density functional calculations on the oxygenation reaction of propene by a model for taurine/ α-ketoglutarate dioxygenase (TauD) enzyme are presented. The oxo-iron active species of TauD is shown to be a powerful and aggressive oxidant, which is able to hydroxylate CH bonds and epoxidize CC bonds...
| Publicado en: | Journal of the American Chemical Society Vol. 128; no. 30; pp. 9813 - 9825 |
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| Formato: | Artículo |
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American Chemical Society
8/2/2006
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=21862021&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 21862021 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 8/2/2006 vid: 128 iid: 30 pid: 997 pub: American Chemical Society artinfo: ui: 21862021 10.1021/ja061581g ppf: 9813 ppct: 12 formats: tig: atl: Propene Activation by the Oxo-Iron Active Species of Taurine/α-Ketoglutarate Dioxygenase (TauD) Enzyme. How Does the Catalysis Compare to Heme-Enzymes? aug: au: de Visser, Sam P. affil: Manchester Interdisciplinary Biocenter, University of Manchester, Sackville Street, P.O. Box 88, Manchester M60 1QD, United Kingdom School of Chemical Engineering and Analytical Science, University of Manchester, Sackville Street, P.O. Box 88, Manchester M60 1QD, United Kingdom su: Propene Density functionals Functional analysis Oxidation-reduction reaction Chemical reactions Surface chemistry sug: subj: Propene Density functionals Functional analysis Oxidation-reduction reaction Chemical reactions Surface chemistry ab: Density functional calculations on the oxygenation reaction of propene by a model for taurine/ α-ketoglutarate dioxygenase (TauD) enzyme are presented. The oxo-iron active species of TauD is shown to be a powerful and aggressive oxidant, which is able to hydroxylate CH bonds and epoxidize CC bonds with low barriers. In the case of propene oxygenation, the hydroxylation and epoxidation mechanisms are competitive on a dominant quintet spin state surface. We have compared the mechanism and thermodynamics of TauD with oxo-iron heme catalysts, such as the cytochromes P450, and found some critical differences. The TauD model is found to be much more reactive toward oxygenation of substrates than oxo-iron complexes in a heme environment with much lower reaction barriers. We have analyzed this and assigned this to the strength of the OH bond formed after hydrogen abstraction from a substrate, which is at least 10 kcal mol stronger in five-coordinated oxo-iron nonheme complexes than in six-coordinated oxo-iron heme complexes. Since, the metal in TauD enzymes is five-coordinated, whereas in heme-enzymes it is six-coordinated there are some critical differences in the valence molecular orbitals. Thus, in oxo-iron heme catalysts one of the antibonding π* orbitals is replaced by a low-lying nonbonding δ orbital resulting in a lower overall spin state. Moreover, heme-enzymes have an extra oxidation equivalent located on the heme, which is missing in non-heme oxo-iron catalysts. As a result, the oxo-iron species of TauD reacts via single-state reactivity on a dominant quintet spin state surface, whereas oxo-iron heme catalysts react via two-state reactivity on competing doublet and quartet spin states. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2006 holdings: @attributes: islocal: N |
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