title: Thermodynamic and Structural Investigation of Synthetic Actinide-Peptide Scaffolds.
abstract: The complexation of uranium and europium, in oxidation states +VI and +III, respectively, was investigated with pertinent bio-inorganic systems. Three aspartate-rich pentapeptides with different structural properties were selected for study to rationalize the structure-affinity relationships. Thermodynamic results, crosschecked by both isothermal titration calorimetry and time-resolved laser fluorescence spectroscopy, showed different affinity depending on the peptide for both Eu(III) and U(VI). The thermodynamic aspects were correlated to structural predictions, which were acquired by density functional theory quantum chemical calculations and from IR and extended X-ray absorption fine structure experiments. The combination of these microscopic properties revealed that carbonyl-metal interactions affected the entropy in the case of europium, while the larger uranyl cation was mostly affected by preorganization and steric effects, so that the affinity was enhanced through enthalpy. The approach described here revealed various microscopic aspects governing peptide actinide affinity. Highlighting these mechanisms should certainly contribute to the rational synthesis of higher affinity biomimetic aspartic ligands.
authors.forename: Samir
authors.initials: S
authors.lastname: Safi
authors.forename: Aurélie
authors.initials: A
authors.lastname: Jeanson
authors.forename: Jérome
authors.initials: J
authors.lastname: Roques
authors.affiliation: MARS Beamline, Synchrotron SOLEIL, L'Orme des Merisiers , 91192 Gif-sur-Yvette, France.
authors.forename: Pier Lorenzo
authors.initials: PL
authors.lastname: Solari
authors.forename: Florence
authors.initials: F
authors.lastname: Charnay-Pouget
authors.affiliation: Institut de Chimie de Nice, Université de Nice Sophia Antipolis , 28 Avenue Valrose, 06108 Nice, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Den Auwer
authors.affiliation: Institut de Chimie de Nice, Université de Nice Sophia Antipolis , 28 Avenue Valrose, 06108 Nice, France.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Creff
authors.forename: David J
authors.initials: DJ
authors.lastname: Aitken
authors.forename: Eric
authors.initials: E
authors.lastname: Simoni
mesh_terms: D008671:Actinoid Series Elements / Q000737:chemistry*; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D013816:Thermodynamics; D056928:X-Ray Absorption Spectroscopy
chemical_list: D008671:Actinoid Series Elements; D010455:Peptides