Osteopontin: A Uranium Phosphorylated Binding‐Site Characterization |
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Authors: | Dr Samir Safi Dr Gaëlle Creff Dr Aurélie Jeanson Lei Qi Christian Basset Dr Jérome Roques Dr Pier Lorenzo Solari Prof Eric Simoni Dr Claude Vidaud Prof Christophe Den Auwer |
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Institution: | 1. Groupe Radiochimie, Institut de Physique Nucléaire d'Orsay, Université Paris XI Orsay, 15 Rue Georges Clemenceau, 91405 Orsay (France);2. Institut de Chimie de Nice, Université de Nice Sophia Antipolis, 28 Avenue Valrose, 06108 Nice (France);3. Life Science Division, DSV, CEA Marcoule, 30207 Bagnols sur Cèze (France);4. State Key Laboratory of Agro‐biotechnology and College of Biological Sciences, China Agricultural University, Beijing (P. R. China);5. MARS beamline, Synchrotron SOLEIL, L‘Orme des Merisiers, 91192 Gif sur Yvette (France) |
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Abstract: | Herein, we describe the structural investigation of one possible uranyl binding site inside a nonstructured protein. This approach couples spectroscopy, thermodynamics, and theoretical calculations (DFT) and studies the interaction of uranyl ions with a phosphopeptide, thus mimicking a possible osteopontin (OPN) hydroxyapatite growth‐inhibition site. Although thermodynamical aspects were investigated by using time‐resolved laser fluorescence spectroscopy (TRLFS) and isothermal titration calorimetry (ITC), structural characterization was performed by extended X‐ray absorption fine structure (EXAFS) at the U LIII‐edge combined with attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopy. From the vibrational and fluorescence spectra, several structural models of a UO22+/peptide complex were developed and subsequently refined by using theoretical calculations to fit the experimental EXAFS obtained. The structural effect of the pH value was also considered under acidic to moderately acidic conditions (pH 1.5–5.5). Most importantly, the uranyl/peptide coordination environment was similar to that of the native protein. |
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Keywords: | actinides density functional calculations EXAFS spectroscopy protein structure uranium |
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