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Extension des méthodes d'affinement multipolaire de petites molécules aux macromolécules biologiques : application à la structure de l'Aldose Réductase Humaine résolue à 0.66Â

Abstract : Improvements of macromolecular crystallography regularly push the limits of protein crystals X-ray diffraction. Hence, crystals of the ternary complex Human Aldose Reductase NADP+-inhibitor, diffracting up to 0.65Â resolution, have been obtained. Such a resolution allows to observe the deformation of the electron density due to the chemical environment. In this case, the spherical atom model used in protein crystallography is not adapted, and has to be substituted by a more sophisticated model, like the Hansen & Coppens multipolar atom model, which takes into account this new information. Then the present study concerns the extension of small molecules multipolar refinement methods to subatomic resolution proteins structures, with as application, the charge density study of the Aldose Reductase complex. For this work, we have developed in the LCM[exponent 3]B, on one hand a new software (MOPRO), adapted to classical multipolar refinement methods and to macromolecular crystallography techniques, and on the other hand, an experimental multipolar database describing the average electron density deformation of amino acids and of the NADP+ cofactor. These parameters have then been transferred to the enzyme atomic structure in order to constitute a starting point for the MOPRO multipolar refinement. Our results clearly justify the use of a non-spherical atom model in the case of subatomic resolution protein structures. Furthermore, on the basis of comparisons between experimental and theoretical results, we have shown that the experimental multipolar database parameters are a good descriptions of the active site electrostatic potential. By a more precise modeling of the electron density, these methods will allow a better understanding of the relationships between proteins structure and function.
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http://docnum.univ-lorraine.fr/prive/SCD_T_2002_0027_GUILLOT.pdf
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https://hal.univ-lorraine.fr/tel-01746693
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Submitted on : Thursday, March 29, 2018 - 10:42:49 AM
Last modification on : Thursday, February 25, 2021 - 10:12:02 AM

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  • HAL Id : tel-01746693, version 1

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Benoît Guillot. Extension des méthodes d'affinement multipolaire de petites molécules aux macromolécules biologiques : application à la structure de l'Aldose Réductase Humaine résolue à 0.66Â. Autre [cond-mat.other]. Université Henri Poincaré - Nancy 1, 2002. Français. ⟨NNT : 2002NAN10027⟩. ⟨tel-01746693⟩

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