Protein—Cofactor Interactions and EPR Parameters for the Q Quinone Binding Site of Quinol Oxidase. A Density Functional Study.
Recent multifrequency EPA studies of the "high-affinity" quinone binding site of quinol oxidase (QH site) have suggested a very asymmetric hydrogen-bonding environment for the semiquinone radical anion state. Single-sided hydrogen bonding to the O carbonyl position was one of the proposals, which co...
| Publicado en: | Journal of the American Chemical Society Vol. 128; no. 17; pp. 5659 - 5672 |
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| Autores principales: | , , |
| Formato: | Artículo |
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American Chemical Society
5/3/2006
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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=20912779&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 20912779 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: 5/3/2006 vid: 128 iid: 17 pid: 997 pub: American Chemical Society artinfo: ui: 20912779 10.1021/ja053988b ppf: 5659 ppct: 13 formats: tig: atl: Protein—Cofactor Interactions and EPR Parameters for the Q Quinone Binding Site of Quinol Oxidase. A Density Functional Study. aug: au: Kacprzak, Sylvia Kaupp, Martin MacMillan, Fraser affil: Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D 97074 Würzburg, Germany Institut für Physikalische und Theoretische Chemie, J. W. Goethe Universität Frankfurt, D-60439 Frankfurt am Main, Germany su: Oxidases Proteins Electron paramagnetic resonance Hydrogen bonding Density functionals Quinone Binding sites sug: subj: Oxidases Proteins Electron paramagnetic resonance Hydrogen bonding Density functionals Quinone Binding sites ab: Recent multifrequency EPA studies of the "high-affinity" quinone binding site of quinol oxidase (QH site) have suggested a very asymmetric hydrogen-bonding environment for the semiquinone radical anion state. Single-sided hydrogen bonding to the O carbonyl position was one of the proposals, which contrasts with some previous experimental indications. Here density functional calculations of the EPR parameters (g-tensors, C, ¹H, and Q hyperfine tensors) for a wide variety of supermolecular model complexes have been used to provide insight into the detailed relations among structure, environment, and EPA parameters of ubisemiquinone radical anions. A single-sided binding model is not able to account for the experimentally observed low g component of the g-tensor or for the observed magnitude of the asymmetry of the C carbonyl HFC tensors. Based on the detailed comparison between computation and experiment, a model with two hydrogen bonds to O and one hydrogen bond to O is suggested for the Q site, but a model with one more hydrogen bond on each side cannot be excluded. Several general conclusions on the interrelations between EPA parameters and hydrogen bond patterns of ubisemiquinones in proteins are provided. 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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