Selective and Cooperative Ligand Binding to Antiparallel Human Telomeric DNA G‐Quadruplexes

The quest for ligands that specifically bind to particular G‐quadruplex nucleic acid structures is particularly important to conceive molecules with specific effects on gene expression or telomere maintenance, or conceive structure‐specific molecular probes. Using electrospray mass spectrometry in native conditions, we reveal a highly cooperative and selective 2:1 binding of Cu^II‐tolylterpyridine complexes to human telomeric G‐quadruplexes. Circular dichroism and comparisons of affinities for different sequences reveal a marked preference for antiparallel structures with diagonal loops and/or wide‐medium–narrow‐medium groove‐width order. The cooperativity is attributed to conformational changes in the polymorphic telomeric G‐quadruplex sequences, which convert preferably into an antiparallel three‐quartet topology upon binding of two ligands.     

Effect of rehydration conditions on the catalytic activity of hydrotalcite-derived Mg-Al oxides in aldolization of acetone

Summary Mg-Al hydrotalcite-derived oxides with a varying Mg/Al molar ratio, ranging from 2.6 to 3.2, were rehydrated in the vapor phase at different temperatures (20-90°C). The catalytic performance of the materials obtained was studied in the aldol condensation of acetone. The initial activity of the rehydrated catalysts depended strongly on the Mg/Al molar ratio and the activation temperature. It was found that the re-arrangement of active sites, leading to the reconstruction of hydrotalcite-like phase, occurred during the catalytic test.     

Sigmatropic Rearrangement of Vinyl Aziridines: Expedient Synthesis of Cyclic Sulfoximines from Chiral Sulfinimines

A novel rearrangement of 2‐vinyl aziridine 2‐carboxylates to unusual chiral cyclic sulfoximines is described herein. The method allows the synthesis of substituted cyclic sulfoximines in high yields with complete stereocontrol, and tolerates a wide substrate scope. A one‐pot process starting directly from sulfinimines provides access to complex chiral sulfoximines in only two steps from commercially available aldehydes. A mechanistic hypothesis and synthetic application in the formal synthesis of trachelanthamidine, by transformation of a cyclic sulfoximine into a pyrroline, is also disclosed.     

Hydration,carbonation and thermal stability of hydrates in Ca7−xSrxZrAl6O18 cement

Journal of Thermal Analysis and Calorimetry - This paper studies hydration stages and phase transformation mechanism of the Sr2+-doped calcium zirconium aluminate cement at room temperature....     

The synthesis and spectral properties of new DNA binding ligands

Two new ligands based on anthracene or carbazole planar skeletons, and a phenyloxazoline moiety linked by a vinyl bridge are synthesized as potential DNA-interacting drugs. Their spectral characteristics and DNA binding affinity are assessed.     

Protein stabilization through supramolecular host–guest interactions with cyclodextrin-modified nanoparticles

This study demonstrates the protein stabilization of gelatin through supramolecular interactions of silica nanoparticles and the influence on the point of denaturation. The phenomenon was studied in diluted solutions by dynamic light scattering, viscosity measurements, and differential scanning calorimetry. Native gelatin is stabilized by cyclodextrin functionalized SiO₂ nanoparticles. After heating, increased supramolecular interactions of the nanoparticles with the denaturated gelatin coils are observed by progressive agglomeration. The described observation also resulted in a melting temperature shift from 30 °C, for native gelatin, to about 47 °C for the gelatin/CD-SiO₂, which indicates the supramolecular stabilization of the gelatin chain structure. It was found that the gelatin is supramolecularly immobilized on the nanoparticle up to a certain temperature through complexation by cyclodextrin. The described results, also confirmed by DSC and viscosity measurements, show the prospect of using cyclodextrin-modified surfaces for the immobilization of the proteins.