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Catalases (CAT) are antioxidant metalloenzymes necessary for life in oxygen-metabolizing cells to regulate H2O2concentration by accelerating its dismutation. Many physiopathological situations are associated with oxidative stress resulting from H2O2overproduction, during which antioxidant defenses are overwhelmed. We have used a combinatorial approach associated with an activity-based screening to discover a first peptidyl di-copper complex mimicking CAT. The complex was studied in detail and characterized for its CAT activity both in solutions and in cells using different analytical methods. The complex exhibited CAT activity in solutions and, more interestingly, on HyPer HeLa cells that possess a genetically encoded ratiometric fluorescent sensors of H2O2. These results highlight the efficiency of a combinatorial approach for the discovery of peptidyl complexes that exhibit catalytic activity.

Cells respond to biophysical and biochemical signals. We developed a composite filament from collagen and silica particles modified to interact with collagen and/or present a laminin epitope (IKVAV) crucial for cell–matrix adhesion and signal transduction. This combines scaffolding and signaling and shows that local tuning of collagen organization enhances cell differentiation.

Inorganic complexes are increasingly used for biological and medicinal applications, and the question of the cell penetration and distribution of metallodrugs is key to understanding their biological activity. Oxidative stress is known to be involved in inflammation and in inflammatory bowel diseases for which antioxidative defenses are weakened. We report here the study of the manganese complex Mn1mimicking superoxide dismutase (SOD), a protein involved in cell protection against oxidative stress, using an approach in inorganic cellular chemistrycombining the investigation of Mn1intracellular speciation using mass spectrometry and of its quantification and distribution using electron paramagnetic resonance and spatially resolved X-ray fluorescence with evaluation of its biological activity. More precisely, we have looked for and found the MS signature of Mn1in cell lysates and quantified the overall manganese content. Intestinal epithelial cells activated by bacterial lipopolysaccharide were taken as a cellular model of oxidative stress and inflammation. DNBS-induced colitis in mice was used to investigate Mn1activity in vivo. Mn1exerts an intracellular antiinflammatory activity, remains at least partially coordinated, with diffuse distribution over the whole cell, and functionally complements mitochondrial MnSOD.

Systemic change: A system of transformations between helical structures was observed to be governed by interactions mediated by the electronic effects of substituents, entropic effects, the conformational preferences of organic building blocks, and the coordinative preferences of the metal ion. All of these effects were important, but all must be considered together to allow the prediction of the product observed (see scheme).

Foldamers at an angle: Metal‐directed assembly dictates the perpendicular or parallel orientation of helically folded aromatic oligoamide modules and mediates the communication of their relative handedness (see figure).

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Ab initiocalculations together with vibrational circular dichroism (VCD) are validated as very accurate tools for studying conformations and estimating conformational energies and helical handedness preferences of an entire, large (112 atoms), abiotic foldamer.

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