Structures and DNA-binding and cleavage properties of ternary copper(II) complexes of glycine with phenanthroline, bipyridine, and bipyridylamine

The crystal structures of the series of three complexes, [Cu(Gly)(bpy)Cl].2H2O (1) (Gly=glycine; bpy=2,2'-bipyridine), [Cu(Gly)(phen)Cl]2.7H2O (2) (phen=1,10-phenanthroline), and [Cu(Gly)(bpa)(H2O)Cl] (3) (bpa=2,2'-bipyridylamine) were determined, and the coordination modes of Cu(II) ternary complexes were compared. The central Cu(II) atoms of complexes 1 and 3 have a similar distorted octahedral coordination geometry, while the Cu(II) atom of complex 2 has a distorted square pyramidal coordination. In all complexes, the aromatic heterocyclic compounds bpy, phen, and bpa, behave as a bidentate N,N' ligand, and Gly behaves as a bidentate N,O ligand. DNA-binding properties of the complexes to calf thymus (CT) DNA were studied by using the fluorescence method. Each of the complexes showed binding propensity to CT DNA with the relative order 2>3> or =1. DNA cleavage studies indicate that each of the complexes, especially 2, can cleave plasmid supercoiled pBR322 DNA in the presence of H2O2 and ascorbic acid with cleavage efficiency in the order 2>3 approximately 1. The degradation of the conformation of CT DNA by the complexes was also reflected in the decrease in the intensities of the characteristic CD bands with the relative order 2>3 approximately 1.     

HPLC for stress-free screening of potential prostate cancer marker catechol estrogens in urine using a diamond-electrode electrochemical and a fluorescence detector

Improvement of the sensitivity and specificity of a simultaneous stress-free screening method for catechol estrogens as a potential prostate cancer marker in urine has been accomplished by HPLC with a diamond-electrode electrochemical detector and a fluorescence detector. Since taking urine samples generates less stress (or pain) than the drawing of blood, the method can readily be applied to almost any patient, and will also assist in improving the sensitivity and specificity of the prostatic specific antigen test. Catechol estrogens (2-hydroxyestrone, 4-hydroxyestrone, 2-methoxyestrone, 2-hydroxyestradiol, 4-hydroxyestradiol, 2-methoxyestradiol, and 2-hydroxyestriol) and estrogens (estrone, estradiol, estriol) were separated on an Inertsil ODS-II column with acetonitrile-potassium dihydrogen phosphate (pH 3.0). The diamond-electrode electrochemical detector used had the great advantage of being a maintenance-free system, and could sequentially analyze hundreds of samples. Fluorescence detection improved the sensitivity 10-500 times (e. g., the LOD of 2-hydroxyestriol was improved 250 times) compared to previous electrochemical detection reports, and dual detection improved peak identification in the urine samples. The proposed method was applied to the simultaneous determination of catechol estrogens in spiked urine in a preliminary study on estrogens and PSA values in biopsy and prostate cancer patients.     

Structural change of molybdenum on silica–alumina in contact with propene studied by ESR and Mo LIII-edge XANES

To obtain structural information of the molybdenum species supported on silica–alumina (SAH-1), as a unique catalyst for propene metathesis, Mo L_III-edge XANES and ESR spectroscopies were applied to characterize. The molybdenum species on SAH-1 are partly reduced to form Mo⁵⁺ ions in contact with propene even at room temperature (293 K), and the reduced ions increased with an increase in reaction temperature up to 473 K. From the results of Mo L_III-edge XANES, unique polymolybdate species with tetrahedral and octahedral structures are dominant in MoO₃/SAH-1 before the reaction. After the metathesis reaction, Mo ions are partly reduced to form metathesis active species and a ratio of tetrahedral structure decreases. This unique redox behavior of Mo ions is brought about by SAH-1 support. It is suggested that the metathesis active species of MoO₃/SAH-1 are not highly dispersed Mo ions in reduced state but are in poorly crystallized polymolybdate species, which can be partly reduced in contact with propene even at room temperature.     

Phenanthrene adsorption from solution on single wall carbon nanotubes

Phenanthrene was adsorbed from ethanol solution to the surface of single wall carbon nanotubes, which were previously physically and chemically characterized. Different anionic surfactants were added in the solutions to enhance the phenanthrene solubility and apparently have also improved the dispersion of two respective nanotube samples used. Adsorbed amount was determined through the concentration difference measured by UV-visible spectrophotometry. Results suggest that adsorption of phenanthrene is extremely improved in the case of nanotube purified with higher quality. These findings were confirmed by X-ray photoelectron spectroscopy. The influence of the surfactant on the adsorption kinetics of phenanthrene is suggested to be significant as well.     

fac‐Tris(2‐ethyl‐4‐oxo‐4H‐pyran‐3‐olato‐κ2O3,O4)­iron(III) and its aluminium(III) analog

The crystal structures of the title iron(III) and aluminium(III) ethyl maltolate complexes, [Fe(C₇H₇O₃)₃] and [Al(C₇H₇O₃)₃], respectively, are isomorphous. In each case, the three bidentate ligand mol­ecules are bound to the metal atom, forming a distorted octahedral coordination geometry in a fac configuration.     

Living polymerization of ethylphenylketene by samarium enolate

The living polymerization of ethylphenylketene (EPK) by a samarium enolate is described. Poly(EPK) with controlled molecular weight and low polydispersity was obtained in a quantitative yield by the polymerization with the samarium enolate and polar additives. A wide variety of polar additives including amides and ureas were shown to facilitate the formation of well‐defined poly(EPK).     

Chemical Synthesis of Interleukin-2 and Disulfide Stabilizing Analogues

Chemical protein synthesis allows the construction of well-defined structural variations and facilitates the development of deeper understanding of protein structure–function relationships and new protein engineering strategies. Herein, we report the chemical synthesis of interleukin-2 (IL-2) variants on a multimilligram scale and the formation of non-natural disulfide mimetics that improve stability against reduction. The synthesis was accomplished by convergent KAHA ligations; the acidic conditions of KAHA ligation proved to be valuable for the solubilization of the hydrophobic segments of IL-2. The bioactivity of the synthetic IL-2 and its analogues were shown to be equipotent to recombinant IL-2 and exhibit improved stability against reducing agents.     

The High-Pressure Hexagonal Phase of Long Chain Dicarboxylic Acids in Water

The high pressure phase of several kinds of dicarboxylic acid (DCA) has been studied by X-ray diffraction up to 700 MPa and compared with the hexagonal phase of polyethylene (PE) under high pressure. Eicosanedioic acid (DCA-20) is the shortest DCA investigated that has the high pressure phase. The phase diagram of DCA-20 is determined. Water plays an essential role for the transition from the monoclinic to the hexagonal form; in the absence of water, the monoclinic form directly melts without passing through the hexagonal form. Low molecular weight PE treated by fuming nitric acid is a DCA with a long methylene chain and also has the hexagonal form only in the water as a pressure transmitting fluid. The mechanism of the transition is discussed in the light of hydration of the carboxyl groups on the crystal surface and flexibility of the molecule depending on the length of methylene chain.