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Liaisons par Chélation et Liaisons Hydrogène: une Mesure Directe

Abstract : Living systems use weak bonds (hydrogen bonds, chelation bonds, etc.) to ensure the cohesion of some macromolecular structures (tertiary structure of proteins, double helix of the DNA molecule, etc.) and to allow the formation of some transient structures that need to be formed and broken rapidly (receptor-ligand complexes, ion-amino acid complexes, etc.). The energies of those bonds are not well known because a large number of interactions combine their effects during such processes. One way of probing those energies is the measurement of adhesion energies between surfaces bearing functional groups that are able to form the bonds of interest. A lipid whose headgroup is made of a NTA compound has been used. The three carboxyl groups of the NTA molecule can make hydrogen bonds. Under certain physico-chemical conditions, the NTA group can catch a nickel ion thus forming a chelation bond. Several force measurements have been made using the SFA technique between two lipid bilayers containing either NTA or NTA-Ni lipids. Some of these measurements have been complemented by adhesion energy measurements between functionalized vesicles. Some experiments in water lead to the estimation of the energy of a single hydrogen bond: 1 kBT. Force measurements and vesicle experiments in a Tris buffer lead to a reliable value for the binding energy between two NTA groups sharing a nickel ion: 2 kBT. The NTA-Ni lipid was also used as a tool for anchoring histidine-tagged retinoid receptors to SFA surfaces in order to probe the interaction energy between a retinoid and its receptor. A lipid whose headgroup contains a synthetic retinoid has been used. Force measurements have been made between a monolayer of this retinoid lipid and a monolayer of NTA-Ni lipids carrying the receptors. Force measurements have also been made between two monolayers of retinoid lipids; those measurements revealed very strong adhesion energies due to the combined effect of hydrophobic forces and hydrogen bonds.
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https://tel.archives-ouvertes.fr/tel-00001889
Contributor : David Tareste <>
Submitted on : Wednesday, October 30, 2002 - 12:52:02 PM
Last modification on : Thursday, December 10, 2020 - 12:36:21 PM
Long-term archiving on: : Friday, April 2, 2010 - 8:01:31 PM

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  • HAL Id : tel-00001889, version 1

Citation

David Tareste. Liaisons par Chélation et Liaisons Hydrogène: une Mesure Directe. Biophysique [physics.bio-ph]. Université Pierre et Marie Curie - Paris VI, 2002. Français. ⟨tel-00001889⟩

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