Biomimetic Pseudopeptides to Decipher the Interplay Between Cu and Methionine-Rich Domains in Proteins.

Maintaining tightly copper homeostasis is crucial for the survival of all living organisms, in particular microorganisms like bacteria. They have evolved a number of proteins to capture, transport and deliver Cu(I), while avoiding Fenton-like reactions. Some Cu proteins exhibit methionine-rich (Met-rich) domains, whose role remains elusive.

Hydrophilic interaction liquid chromatography: An efficient tool for assessing thorium interaction with phosphorylated biomimetic peptides.

In the field of nuclear toxicology, the knowledge of the interaction of actinides (An) with biomolecules is of prime concern in order to elucidate their toxicity mechanism and to further develop selective decorporating agents. In this work, we demonstrated the great potential of hydrophilic interaction liquid chromatography (HILIC) to separate polar thorium (Th) biomimetic peptide complexes, as a key starting point to tackle these challenges. Th was used as plutonium (Pu) analogue and pS16 and pS1368 as synthetic di- and tetra-phosphorylated peptides capable of mimicking the interaction sites of these An in osteopontin (OPN), a hyperphosphorylated protein.

Outstanding Superoxide Dismutase Catalytic Activity Of Simple Peptide-Based Nickel(II) Complexes.

We present here the most active synthetic Ni superoxide dismutase (NiSOD) mimic reported to date. Reactive oxygen species are aggressive compounds, which concentrations are tightly regulated in vivo. Among them, the superoxide anion, O⋅, is controlled by superoxide dismutases.

Determining the selectivity of a tetra-phosphorylated biomimetic peptide towards uranium in the presence of competing cations through the simultaneous coupling of HILIC to ESI-MS and ICP-MS.

A cyclic tetra-phosphorylated biomimetic peptide (pS1368) has been proposed as a promising starting structure to design a decorporating agent of uranyl (UO) due to its affinity being similar to that of osteopontin (OPN), a target UO protein in vivo. The determination of this peptide's selectivity towards UO in the presence of competing endogenous elements is also crucial to validate this hypothesis. In this context, the selectivity of pS1368 towards UO in the presence of Ca, Cu and Zn was determined by applying the simultaneous coupling of hydrophilic interaction chromatography (HILIC) to electrospray ionization (ESI-MS) and inductively coupled plasma (ICP-MS) mass spectrometry.

A Series of Ni Complexes Based on a Versatile ATCUN-Like Tripeptide Scaffold to Decipher Key Parameters for Superoxide Dismutase Activity.

The cellular level of reactive oxygen species (ROS) has to be controlled to avoid some pathologies, especially those linked to oxidative stress. One strategy for designing antioxidants consists of modeling natural enzymes involved in ROS degradation. Among them, nickel superoxide dismutase (NiSOD) catalyzes the dismutation of the superoxide radical anion, O, into O and HO.

Tristhiolato Pseudopeptides Bind Arsenic(III) in an AsS Coordination Environment Imitating Metalloid Binding Sites in Proteins.

The As binding of two NTA-based tripodal pseudopeptides, possessing three cysteine (ligand ) or d-penicillamine residues (ligand ) as potential coordinating groups for soft semimetals or metal ions, was studied by experimental (UV, CD, NMR, and ESI-MS) and theoretical (DFT) methods. All of the experimental data, obtained with the variation of the As:ligand concentration ratios or pH values in some instances, evidence the exclusive formation of species with an AsS-type coordination mode. The UV-monitored titration of the ligands with arsenous acid at pH = 7.

Determination of the affinity of biomimetic peptides for uranium through the simultaneous coupling of HILIC to ESI-MS and ICP-MS.

Several proteins have been identified in the past decades as targets of uranyl (UO) in vivo. However, the molecular interactions responsible for this affinity are still poorly known which requires the identification of the UO coordination sites in these proteins. Biomimetic peptides are efficient chemical tools to characterize these sites.

The plasma membrane-associated cation-binding protein PCaP1 of Arabidopsis thaliana is a uranyl-binding protein.

Uranium (U) is a naturally-occurring radionuclide that is toxic to living organisms. Given that proteins are primary targets of U(VI), their identification is an essential step towards understanding the mechanisms of radionuclide toxicity, and possibly detoxification. Here, we implemented a chromatographic strategy including immobilized metal affinity chromatography to trap protein targets of uranyl in Arabidopsis thaliana.

Optimized Coordination of Uranyl in Engineered Calmodulin Site 1 Provides a Subnanomolar Affinity for Uranyl and a Strong Uranyl versus Calcium Selectivity.

As an alpha emitter and chemical toxicant, uranium toxicity in living organisms is driven by its molecular interactions. It is therefore essential to identify main determinants of uranium affinity for proteins. Others and we showed that introducing a phosphoryl group in the coordination sphere of uranyl confers a strong affinity of proteins for uranyl.

A Simple Fluorescence Affinity Assay to Decipher Uranyl-Binding to Native Proteins.

Determining the affinity of proteins for uranyl is key to understand the toxicity of this cation and to further develop decorporation strategies. However, usual techniques to achieve that goal often require specific equipment and expertise. Here, we propose a simple, efficient, fluorescence-based method to assess the affinity of proteins and peptides for uranyl, at equilibrium and in buffered solution.

Development, formulation, and cellular mechanism of a lipophilic copper chelator for the treatment of Wilson's disease.

Copper homeostasis is finely regulated in human to avoid any detrimental impact of free intracellular copper ions. Upon copper accumulation, biliary excretion is triggered in liver thanks to trafficking of the ATP7B copper transporter to bile canaliculi. However, in Wilson's disease this protein is mutated leading to copper accumulation.

A Bioinspired Ni Superoxide Dismutase Catalyst Designed on an ATCUN-like Binding Motif.

Nickel superoxide dismutase (NiSOD) is an enzyme that protects cells against O. While the structure of its active site is known, the mechanism of the catalytic cycle is still not elucidated. Its active site displays a square planar Ni center with two thiolates, the terminal amine and an amidate.

Tripodal scaffolds with three appended imidazole thiones for Cu(I) chelation and protection from Cu-mediated oxidative stress.

Imidazole thiones appear as interesting building blocks for Cu(I) chelation and protection against Cu-mediated oxidative stress. Therefore, a series of tripodal molecules derived from nitrilotriacetic acid appended with three imidazole thiones belonging either to histamine-like or histidine-like moieties were synthesized. These tripods demonstrate intermediate affinity between that previously measured for tripodal analogues bearing three thiol moieties such as cysteine and those grafted with three thioethers, like methionines, consistently with the thione group in the imidazole thione moiety existing as a tautomer between a thiol and a thione.

Separation of multiphosphorylated cyclopeptides and their positional isomers by hydrophilic interaction liquid chromatography (HILIC) coupled to electrospray ionization mass spectrometry (ESI-MS).

Peptides are efficient models used in different fields such as toxicology to study the interactions of several contaminants at the molecular scale, requiring the development of bio-analytical strategies. In this context, Hydrophilic interaction liquid chromatography (HILIC) coupled to electrospray ionization mass spectrometry (ESI-MS) was used to separate synthetic multiphosphorylated cyclopeptides and their positional isomers at physiological pH. We assessed (i) the selectivity of eleven HILIC columns, from different manufacturers and packed with diverse polar sorbents, and (ii) the effect of mobile phase composition on the separation selectivity.

Lectin recognition and hepatocyte endocytosis of GalNAc-decorated nanostructured lipid carriers.

Liver is the main organ for metabolism but is also subject to various pathologies, from viral, genetic, cancer or metabolic origin. There is thus a crucial need to develop efficient liver-targeted drug delivery strategies. Asialoglycoprotein receptor (ASGPR) is a C-type lectin expressed in the hepatocyte plasma membrane that efficiently endocytoses glycoproteins exposing galactose (Gal) or N-acetylgalactosamine (GalNAc).

A liver-targeting Cu(i) chelator relocates Cu in hepatocytes and promotes Cu excretion in a murine model of Wilson's disease.

Copper chelation is the most commonly used therapeutic strategy nowadays to treat Wilson's disease, a genetic disorder primarily inducing a pathological accumulation of Cu in the liver. The mechanism of action of Chel2, a liver-targeting Cu(i) chelator known to promote intracellular Cu chelation, was studied in hepatic cells that reconstitute polarized epithelia with functional bile canaliculi, reminiscent of the excretion pathway in the liver. The interplay between Chel2 and Cu localization in these cells was demonstrated through confocal microscopy using a fluorescent derivative and nano X-ray fluorescence.

In vitro assessment of cobalt oxide particle dissolution in simulated lung fluids for identification of new decorporating agents.

Inhalation of CoO particles may occur at the work place in nuclear industry. Their low solubility may result in chronic lung exposure to γ rays. Our strategy for an improved therapeutic approach is to enhance particle dissolution to facilitate cobalt excretion, as the dissolved fraction is rapidly eliminated, mainly in urine.

Safer-by-design biocides made of tri-thiol bridged silver nanoparticle assemblies.

Silver nanoparticles (AgNPs) are efficient biocides increasingly used in consumer products and medical devices. Their activity is due to their capacity to release bioavailable Ag(i) ions making them long-lasting biocides but AgNPs themselves are usually easily released from the product. Besides, AgNPs are highly sensitive to various chemical environments that triggers their transformation, decreasing their activity.

Recent advances in uranyl binding in proteins thanks to biomimetic peptides.

Uranium is an element belonging to the actinide series. It is ubiquitous in rock, soil, and water. Uranium is found in the ecosystem due to mining and milling industrial activities and processing to nuclear fuel, but also to the extensive use of phosphate fertilizers.

Quantification of Surface GalNAc Ligands Decorating Nanostructured Lipid Carriers by UPLC-ELSD.

Nanoparticles have been extensively studied for drug delivery and targeting to specific organs. The functionalization of the nanoparticle surface by site-specific ligands (antibodies, peptides, saccharides) can ensure efficient recognition and binding with relevant biological targets. One of the main challenges in the development of these decorated nanocarriers is the accurate quantification of the amount of ligands on the nanoparticle surface.

Mononuclear Ni(II) Complexes with a S3O Coordination Sphere Based on a Tripodal Cysteine-Rich Ligand: pH Tuning of the Superoxide Dismutase Activity.

The superoxide dismutase (SOD) activity of mononuclear Ni complexes, whose structures are inspired by the NiSOD, has been investigated. They have been designed with a sulfur-rich pseudopeptide ligand, derived from nitrilotriacetic acid (NTA), where the three acid functions are grafted with cysteines (). Two mononuclear complexes, which exist in pH-dependent proportions, have been fully characterized by a combination of spectroscopic techniques including H NMR, UV-vis, circular dichroism, and X-ray absorption spectroscopy, together with theoretical calculations.

Citrulline stimulates muscle protein synthesis, by reallocating ATP consumption to muscle protein synthesis.

Background: Animal studies and clinical data support the interest of citrulline as a promising therapeutic for sarcopenia. Citrulline is known to stimulate muscle protein synthesis, but how it affects energy metabolism to support the highly energy-dependent protein synthesis machinery is poorly understood.

Methods: Here, we used myotubes derived from primary culture of mouse myoblasts to study the effect of citrulline on both energy metabolism and protein synthesis under different limiting conditions.

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

Some phosphoproteins such as osteopontin (OPN) have been identified as high-affinity uranyl targets. However, the binding sites required for interaction with uranyl and therefore involved in its toxicity have not been identified in the whole protein. The biomimetic approach proposed here aimed to decipher the nature of these sites and should help to understand the role of the multiple phosphorylations in UO binding.

Short oligopeptides with three cysteine residues as models of sulphur-rich Cu(i)- and Hg(ii)-binding sites in proteins.

The essential Cu(i) and the toxic Hg(ii) ions possess similar coordination properties, and therefore, similar cysteine rich proteins participate in the control of their intracellular concentration. In this work we present the metal binding properties of linear and cyclic model peptides incorporating the three-cysteine motifs, CxCxxC or CxCxC, found in metallothioneins. Cu(i) binding to the series of peptides at physiological pH revealed to be rather complicated, with the formation of mixtures of polymetallic species.

Mercury Trithiolate Binding (HgS) to a de Novo Designed Cyclic Decapeptide with Three Preoriented Cysteine Side Chains.

Mercury(II) is an unphysiological soft ion with high binding affinity for thiolate ligands. Its toxicity lies in the interactions with low molecular weight thiols including glutathione and cysteine-containing proteins that disrupt the thiol balance and alter vital functions. However, mercury can also be detoxified via interactions with Hg(II)-responsive regulatory proteins such as MerR, which coordinates Hg(II) with three cysteine residues in a trigonal planar fashion (HgS coordination).