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APPLICATION DE LA RESONANCE PARAMAGNETIQUE ELECTRONIQUE A CHAMP INTENSE A L'ETUDE DE RADICAUX ORGANIQUES DANS LES METALLOPROTEINES

Abstract : The importance of organic radicals in enzyme catalytic cycles have been increasingly realized over the past few years. High-field electron paramagnetic resonance (EPR) is a tool of choice in the study of organic radicals because the small g anisotropy for such paramagnetic species can be accurately measured. A 285 GHz / 10.5 T spectrometer has been built in the Bioenergetic Section of the CEA center in Saclay. The work presented in this thesis dealt with the application of high-field EPR to the study of organic radicals encountered in photosystem II, the enzyme responsible for oxygen evolution, as well as in compound I of two peroxidases, cytochrome c peroxidase and prostaglandin synthase.
The first chapter presents the technique of high-field EPR in general and introduces the instrumentation. General aspects of photosystem II useful in the subsequent parts are also presented.
The second chapter shows how anisotropic properties of the g tensor have been used to obtain structural information about the orientation of organic radicals in photosystem II.
Enzymes studied in this thesis are metalloproteins. Cases of magnetic couplings between metallic centers and organic radicals are often encountered for such systems. Chapters 3 to 5 deal with the study of such coupled systems in photosystem II, cytochrome c peroxidase and prostaglandin synthase.
The last chapter present situations for which the study of the g-values gives information on the electrostatic environment of the radical studied. This property, already known for tyrosyl and semiquinone radicals, is extended to pheophytin anion radicals.
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https://tel.archives-ouvertes.fr/tel-00276417
Contributor : Pierre Dorlet <>
Submitted on : Tuesday, April 29, 2008 - 3:51:10 PM
Last modification on : Thursday, November 12, 2020 - 4:10:05 PM
Long-term archiving on: : Friday, May 28, 2010 - 5:07:43 PM

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  • HAL Id : tel-00276417, version 1

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Pierre Dorlet. APPLICATION DE LA RESONANCE PARAMAGNETIQUE ELECTRONIQUE A CHAMP INTENSE A L'ETUDE DE RADICAUX ORGANIQUES DANS LES METALLOPROTEINES. Autre. Université Paris Sud - Paris XI, 2000. Français. ⟨tel-00276417⟩

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