[Fe-Fe]-hydrogenases are enzymes that reversibly catalyze the reaction of protons and electrons to molecular hydrogen, which occurs in anaerobic media. In living systems, [Fe-Fe]-hydrogenases are mostly used for H(2) production. The [Fe-Fe]-hydrogenase H-cluster is the active site, which contains two iron atoms. The latest theoretical investigations1,2 advocate that the structure of di-iron air...

Three macrocyclic oligocholates containing a carboxyl group, a guanidinium ion, and a Cbz-protected amine, respectively, were studied as membrane transporters for hydrophilic molecules. To permeate glucose across lipid bilayers, the macrocycles stacked over one another to form a transmembrane nanopore, driven by a strong tendency of the water molecules in the internal cavities of the amphiphili...

The reaction between aqueous Fe(II) and Fe(III) oxides is extremely complex, and can catalyze Fe(II)-Fe(III) electron transfer, exchange of Fe atoms between the aqueous and solid phases, mineral transformation, and contaminant reduction. Together, these processes represent a phenomenon referred to as Fe(II)-catalyzed Fe oxide recrystallization, which has been observed under controlled condition...

Abstract In order to develop a new class of macro cyclic receptors with a unique shape and set of functional groups the synthesis of novel aromatic dialdehydes I and II using mild conditions oxidation (Mn02) and dibromination-dilithiation methodology has been carried out. Conditions of the oxidation step have been optimised. The study of the reactivity of the dicarboxyaldehydes I and II, in the...

Strains lacking and overexpressing the vacuolar iron (Fe) importer CCC1 were characterized using Mössbauer and EPR spectroscopies. Vacuolar Fe import is impeded in Δccc1 cells and enhanced in CCC1-up cells, causing vacuolar Fe in these strains to decline and accumulate, respectively, relative to WT cells. Cytosolic Fe levels should behave oppositely. The Fe content of Δccc1 cells grown under lo...

Container-molecules are attractive to chemists due to their unique structural characteristics comparable to enzymes and receptors in nature. We report here a family of artificial self-assembled macrocyclic containers that feature induced-fit transformations in response to different anionic guests. Five metal-organic macrocycles with empirical formula of MnL2n (M=Metal; L=Ligand; n=3, 4, 5, 6, 7...

Complexes with purely pyridine-based macrocycles are rarely studied in photo(electro)catalysis. We synthesized and investigated macrocycles, in which two 2,2'-bipyridine (bpy) units are linked twice by two cyano-methylene groups, to yield the basic tetradentate, bipyridine based ligand framework (pyr). The protons in the bridges were substituted to obtain derivatives with one (pyr-alk) or two (...

Iron (Fe) and manganese (Mn) are the two most common redox-active elements in the Earth's crust and are well known to influence mineral formation and dissolution, trace metal sequestration, and contaminant transformations in soils and sediments. Here, we characterized the reaction of aqueous Fe(II) with pyrolusite (β-MnO2) using electron microscopy, X-ray diffraction, aqueous Fe and Mn analyses...

We prepared a series of peptide-like 14-membered macrocycles containing an imidazole-4,5-dicarboxylic acid scaffold by using known coupling reagents and protecting group strategies. Yields of the purified macrocycles were poor on average, yet seemingly independent of amino acid substitution or stereochemistry. The macrocycles retain some level of conformational variability as observed by both m...

Mimosine, DNA breaKs, Free Radicals, Fenton Reaction Supercoiled plasmid DNA was treated in vitro with H2O2, DTT and either Fe (II), Fe (II)-EDTA or Fe (II)-mimosine. The rate of DNA break formation was followed by the conversion of the supercoiled form into relaxed-circular and linear forms. In the concentration interval of 0-4 microM Fe (II), Fe (II)-EDTA slowed-down the formation of DNA brea...