Mid- and Far-Infrared Marker Bands of the Metal Coordination Sites of the Histidine Side Chains in the Protein Cu,Zn-Superoxide Dismutase

International audienceVibrational spectroscopy gives important information on the properties of ligand and metal–ligand bonds in metalloenzymes. Infrared spectroscopy is appealing for the study of metal active sites that are not amenable to Raman spectroscopy. We present a combined experimental and theoretical approach to analyze the mid- and far-IR spectra of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) as a probe of the histidine ligands. This metalloenzyme provides a unique model to identify specific IR signatures of metal–histidine coordination and to study their alterations as a function of the metal (copper/zinc), the copper valence state (+I/+II), the histidine coordination mode (Nτ and Nπ) and the histidine protonation state. DFT calculations combined with normal mode descriptions from potential energy distribution calculations were performed on two slightly different cluster models. Differences in the constraints at the side chain of one histidine Cu ligand sensibly modify the geometric parameters and vibrational properties. Electrochemically induced FTIR difference spectroscopy provided mid- and far-IR fingerprint spectra of the Cu protein in aqueous media that are sensitive to the redox state of the Cu centre at the active site. Comparisons of the DFT predictions with the experimental IR modes of the histidine ligands at the Cu,Zn-SOD active site showed that useful mid-IR markers of histidine Nτ and Nπ coordination were predicted with good accuracy. The DFT analysis further demonstrated a link between the ν(C4–C5) mode frequency of His46 and the specific properties of the His46–Cu bond in Cu,Zn-SOD. A combined theoretical and experimental approach on samples in H2O and 2H2O or 15N-labelled samples identified the contributions from the histidine side chain modes in the 669–629 cm–1 region

Mise au point des conditions de génération in vitro de lymphocytes T cytotoxiques anti-leucémies aiguës lymphoblastiques-T chez l'homme

PARIS-BIUP (751062107) / SudocSudocFranceF

Synthesis of phosphorylated calix[4]arene derivatives for the design of solid phases immobilizing uranyl cations.

International audienceWith the aim of developing supports for uranyl cations immobilization, new 1,3-alternate calix[4]arenes bearing both phosphonic acid functions as chelating sites and N-succinimide-4-oxabutyrate as the anchoring arm were synthesized in good yields. The coupling of such calixarenes to a gel was performed and a successful immobilization of uranyl cations was obtained

Hyphenated CE-ICP/MS : a promising technique to boost the metallomics toolbox

International audienc

Interactions protéine/métal : les potentialités du couplage CE-ICP/M

National audienc

Interactions protéine/métal : les potentialités du couplage CE-ICP/M

National audienc

Phosphate‐Rich Biomimetic Peptides Shed Light on High‐Affinity Hyperphosphorylated Uranyl Binding Sites in Phosphoproteins

International audienc

Investigation of uranium interactions with calcium phosphate-binding proteins using ICP/MS and CE-ICP/MS

The authors thank the Arla Foods Group (J. Viby, Denmark) for providing the Lacprodan (R) sample.International audienceDuring long-term exposure, uranium accumulates in bone. Since uranium in U(VI) complexes shares similar coordination properties to calcium, this toxicant is assumed to be exchanged with calcium ions at the surfaces of bone mineral crystals. Recently, two proteins involved in bone turnover, fetuin A and osteopontin, were shown to exhibit a high affinity for U(VI). A common biochemical feature of both fetuin A and osteopontin is their inhibiting role in calcium phosphate precipitation. Therefore it is conceivable that complexation of U(VI) with these proteins may alter their interaction with calcium and/or calcium phosphate. Quantitative analyses of calcium, phosphorus and uranium performed using inductively coupled plasma/mass spectrometry (ICP/MS) demonstrated the inhibition of the precipitation of calcium phosphate by fetuin A and osteopontin for 2 h. In addition, the presence of U(VI) did not seem to alter the duration of this process. However, dynamic light scattering studies revealed that the size of the colloidal particles formed with osteopontin was altered by the presence of U(VI) in a concentration-dependent manner. Finally, using hyphenated capillary electrophoresis-ICP/MS (CE-ICP/MS), we showed that in these systems, at a low concentration of U(VI) (protein : U(VI) 8 : 1), U(VI) might remain in solution by forming a complex with proteins and not by sequestration of a precipitate of either autunite or uranyl orthophosphate

Design of Double Stimuli-Responsive Polyelectrolyte Microcontainers for Protein Soft Encapsulation

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