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Metal Ion Complexes (metal + ion_complex)
Selected AbstractsComplexes of glutathione with heavy metal ions as a new biochemical marker of aquatic environment pollution,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2010Jiri Baloun Abstract Reduced glutathione (GSH) plays a number of key roles in many biochemical pathways. This peptide is highly reactive and forms conjugates with other molecules via its sulfhydryl moiety. The interactions of the common heavy metal pollutant Cd(II) with GSH were determined by using the Brdicka reaction to evaluate whether this technique would be suitable as a biomarker. After GSH interaction with Cd(II) ions, two characteristic changes in the measured voltammogram were observed: Cat2 signal height decreased, and a new signal called P1 was found. The observed signal probably relates to the formation of a GSH,heavy metal ion complex adsorbed on the surface of the working electrode. When the interaction of GSH with cisplatin was studied, the same characteristic changes in the voltammogram were observed, which confirmed our hypothesis. Moreover, changes in the height of P1 and Cat2 signals with increasing time of GSH interaction with Cd(II) ions and/or cisplatin were also investigated. Cat2 peak height decreased proportionally with increasing time of interaction. This decrease can be explained by shielding of free sulfhydryl moiety by heavy metal ions, so it cannot catalyze the evolution of hydrogen from the supporting electrolyte. In addition, we found that, with increasing time of the interaction, the P1 signal was enhanced and shifted to more positive potentials for both Cd(II) ions and cisplatin. Environ. Toxicol. Chem. 2010;29:497,500. © 2009 SETAC [source] A New Carrier for Selective Removal of Heavy Metal Ions from Aqueous Solutions through Bulk Liquid MembranesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2004Nicoletta Spreti Abstract The carrier-mediated transport of heavy metal ions through bulk liquid membranes has been examined: toxic Hg2+, Cd2+ and Pb2+ ions were studied, along with Cu2+ ions for comparative purposes. The ability of a new carrier, 2,2,-bis(p -octyloxybenzyl)diethylenetriamine (bis- pODET), to complex and transport all the selected metal ions is reported. Differing affinities of the carrier for the different metal ions and the different experimental conditions required for their release into the receiving phase allowed the selective separation of equimolar binary mixtures. For Hg2+/Cd2+ and Hg2+/Pb2+ mixtures, two different separation methods were performed, while the inefficacy of the separation of Cd2+/Pb2+ and Hg2+/Cu2+ mixtures was for two different reasons: (i) the carrier is able to extract the metal ions with similar levels of ability, and (ii) the carrier metal ion complexes require the same acidity of the receiving phase to release the metal ions. The capability of the carrier to transport Hg2+ efficiently in consecutive cycles is also reported: over 90% of the metal ions were transferred into the receiving phase for three consecutive processes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Autophosphorylation of Archaeoglobus fulgidus Rio2 and crystal structures of its nucleotide,metal ion complexesFEBS JOURNAL, Issue 11 2005Nicole LaRonde-LeBlanc The highly conserved, atypical RIO serine protein kinases are found in all organisms, from archaea to man. In yeast, the kinase activity of Rio2 is necessary for the final processing step of maturing the 18S ribosomal rRNA. We have previously shown that the Rio2 protein from Archaeoglobus fulgidus contains both a small kinase domain and an N-terminal winged helix domain. Previously solved structures using crystals soaked in nucleotides and Mg2+ or Mn2+ showed bound nucleotide but no ordered metal ions, leading us to the conclusion that they did not represent an active conformation of the enzyme. To determine the functional form of Rio2, we crystallized it after incubation with ATP or ADP and Mn2+. Co-crystal structures of Rio2,ATP,Mn and Rio2,ADP,Mn were solved at 1.84 and 1.75 Å resolution, respectively. The ,-phosphate of ATP is firmly positioned in a manner clearly distinct from its location in canonical serine kinases. Comparison of the Rio2,ATP,Mn complex with the Rio2 structure with no added nucleotides and with the ADP complex indicates that a flexible portion of the Rio2 molecule becomes ordered through direct interaction between His126 and the ,-phosphate oxygen of ATP. Phosphopeptide mapping of the autophosphorylation site of Rio2 identified Ser128, within the flexible loop and directly adjacent to the part that becomes ordered in response to ATP, as the target. These results give us further information about the nature of the active site of Rio2 kinase and suggest a mechanism of regulation of its enzymatic activity. [source] Preparation and characterization of polymer/multiwall carbon nanotube/nanoparticle nanocomposites and preparation of their metal complexesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010Ahmad Nozad Golikand Abstract Carbon nanotube-polymer nanocomposites were synthesized and characterized successfully. In this work, multiwall carbon nanotubes (MWCNT) were opened using HNO3/H2SO4 mixture and filled by metal nanoparticles such as silver nanoparticles through wet-chemistry method. The oxidized MWCNT were reacted subsequently with thionyl chloride, 1,6-diaminohexane, producing MWNT-amine functionalized. Then the MWCNT containing metal nanoparticles were used as a monomer with different weight percentages in melt polymerization with An and CNCl separately. Furthermore, the polyamide and polytriazine modified MWCNT were used for the preparation of metal ion complexes such as Fe+2 and La+3. The structures and properties of nanocomposites were evaluated by TEM, DSC, TGA, and FT-IR methods. The chelating behavior and sorption capacities of prepared nanocomposites were carried out by using some metal ions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Catalysis in electron transfer reactions: facts and mechanistic insights,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8 2002Shunichi Fukuzumi Abstract Catalysis in electron transfer reactions between electron donors and acceptors is described and the important mechanistic insight is provided by showing a number of examples of both thermal and photochemical reactions that involve metal ion-catalyzed electron transfer processes as the rate-determining steps. The quantitative measure of Lewis acidity of metal ions was obtained from the gzz values of ESR spectra of superoxide,metal ion complexes which vary significantly depending on the type of metal ions. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||