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Étude de complexes à forte diffusion anomale pour la détermination rapide de la structure de protéines par la méthode MAD

Abstract : For the de novo structure resolution of proteins by crystallography, it is necessary to calculate the phases of the structure factors from the diffracted X-ray intensities. For this purpose, the SAD and MAD methods take advantage of the anomalous scattering properties of atoms inside the protein crystals. The introduction of the anomalous scatterers into the crystals is one of the key steps of protein structure resolution.
We have investigated a class of eight gadolinium complexes used to introduce the anomalous scatterers into the protein crystals. Gadolinium exhibits high anomalous scattering with a laboratory X-ray generator as well as in its LIII absorption edge.
A crystallographic study carried out with the class of complexes and eight different proteins allowed to demonstrate the great potential of the complexes for the preparation of derivatives with high phasing power. Indeed, for a great number of derivatives, the calculated experimental phases have led to experimental electron-density maps of excellent quality, allowing the easy construction of the protein model.
The refinement of the structure of the complexes bound to the proteins allowed to gain understanding of the interaction between the different complexes and the proteins.
The utilization of the complexes allowed the structure resolution of four new proteins.
Besides the crystallographic studies we attempted to detect the binding of a complex to a protein with different physico-chemical methods taking into consideration the weak binding constant that characterizes the interaction.
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https://tel.archives-ouvertes.fr/tel-00011238
Contributor : Meike Stelter <>
Submitted on : Monday, December 19, 2005 - 3:28:06 PM
Last modification on : Tuesday, October 6, 2020 - 4:12:03 PM
Long-term archiving on: : Saturday, April 3, 2010 - 7:38:26 PM

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  • HAL Id : tel-00011238, version 1

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Meike Stelter. Étude de complexes à forte diffusion anomale pour la détermination rapide de la structure de protéines par la méthode MAD. Biophysique [physics.bio-ph]. Université Joseph-Fourier - Grenoble I, 2005. Français. ⟨tel-00011238⟩

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