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La Dynamique Moléculaire dans les Globules Rouges

Abstract : Incoherent quasielastic and elastic neutron scattering were used to measure protein and cell water dynamics in the picosecond time and Ångstrom length scale. Hemoglobin dynamics was measured in human red blood cells, in vivo. The experiments revealed a change in the geometry of internal protein dynamics at 36.9°C, human body temperature. Above this temperature amino acid side-chain dynamics occupy larger volumes than expected from normal temperature dependence. Global macromolecular diffusion was interpreted according to theoretical concepts for short-time self-diffusion of non-charged hard sphere colloids. The influence of hydration on hemoglobin dynamics was studied with neutron scattering. The residence times of localized jumps in the order of a few picoseconds were found to be significantly reduced in concentrated solution compared to fully hydrated powder. The change in the geometry of amino acid side-chain dynamics at body temperature was found in concentrated hemoglobin solution, but the body temperature transition in protein dynamics was absent in fully hydrated powder. This indicated that picosecond protein motions responsible for the body temperature transition are activated only at a sufficient level of hydration, and that hydrated powders may not reflect fully all functional protein dynamics. The dynamics of cell water in human red blood cells was measured with quasielastic incoherent neutron scattering. A major fraction of around 90% of cell water is characterized by a translational diffusion coefficient similar to bulk water. A minor fraction of around 10% of cellular water exhibits reduced dynamics. The slow water fraction was attributed to dynamically bound water on the surface of hemoglobin, which accounts for approximately half of the hydration layer.
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https://tel.archives-ouvertes.fr/tel-00442206
Contributor : Andreas Stadler <>
Submitted on : Friday, December 18, 2009 - 4:12:04 PM
Last modification on : Friday, December 18, 2009 - 5:32:19 PM
Long-term archiving on: : Saturday, November 26, 2016 - 2:55:42 PM

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  • HAL Id : tel-00442206, version 1

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Andreas Stadler. La Dynamique Moléculaire dans les Globules Rouges. Biophysique [physics.bio-ph]. Université Joseph-Fourier - Grenoble I, 2009. Français. ⟨tel-00442206⟩

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