Interaction Of Lanthanides Research Articles

Lanthanide interactions with nitrotyrosine. A specific binding site for nuclear magnetic resonance shift probes in proteins.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLanthanide interactions with nitrotyrosine. Specific binding site for nuclear magnetic resonance shift probes in proteinsTimothy D. Marinetti, Grayson H. Snyder, and Brian D. SykesCite this: J. Am. Chem. Soc. 1975, 97, 22, 6562–6570Publication Date (Print):October 1, 1975Publication History Published online1 May 2002Published inissue 1 October 1975https://doi.org/10.1021/ja00855a046RIGHTS & PERMISSIONSArticle Views65Altmetric-Citations38LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Ion‐Binding to Phospholipids

Surface chemical and nuclear magnetic resonance (NMR) techniques have been used to study the interaction of Ca2+ and lanthanides with lecithins. With both methods positive reactions were detected at metal concentrations greater than 0.1 mM. 1H and 31P high-resolution NMR spectra obtained with single bilayer vesicles of lecithin were invariant up to Ca2+ concentrations of 0.1 M indicating that there is only a loose association between Ca2+ and the phospholipid. The weak interaction between Ca2+ and lecithin is confirmed by both surface chemical and NMR techniques showing that the packing of egg lecithin molecules present in bilayers does not change up to Ca2+ concentrations of about 0.1 M. The packing was also independent of pH between 1--10. Contradictory results have been reported in the literature concerning the question of Ca2+ binding to lecithins. The conflicting results are shown to have arisen from differences in the experimental conditions and differences in the sensitivity of the physical methods used by various authors to study Ca2+ -lecithin interactions. An estimate of the strength of binding and molecular details of the interaction were derived using paramagnetic lanthanides as isomorphous replacements for Ca2+. From the changes in chemical shifts induced in the presence of lanthanides an apparent binding constant KA approximately 30 l/mol was calculated at lanthanide concentrations greater than 10 mM. Using surface chemical methods it was shown that this KA is up to 10 times larger than that for Ca2+ binding. The complete assignment of the 1H NMR spectrum of lecithin, including the resonances from the relatively immobilized glycerol group, was determined to derive molecular details of the cation-lecithin interaction. From spin-lattice relaxation-time measurements and line broadening in the presence of GdCl3 it is concluded that the cations are bound to the phosphate group and that this is the only binding site. The absolute proton shifts induced by paramagnetic lanthanides depended on the nature of the ion, but the shift ratios standardised to the shift of the O3POCH2 (choline) signal were invariant throughout the lanthanide series indicating that the shifts are purely pseudocontact. In contrast the 31P shifts were found to contain significant contact contributions. These findings are consistent with a weak interaction and with the phosphate group being the binding site. The absolute shifts but not the shift ratios depended on the anion present indicating that the cation binding may be accompanied by binding of anions. Contrary to negatively charged phospholipids the interaction of lanthanides with lecithins was enhanced as the ionic strength was increased by adding NaCl. This was explained in terms of steric hindrance due to the extended conformation of the lecithin polar group.

Interaction of lanthanide shift reagents with organophosphorus substrates

The interaction of lanthanide (β-diketonate) 3 shift reagents (LSR) with a variety of tricoordinate and tetracoordinate organophosphorus substrates has been examined. In each case, sizable proton and 31P induced shifts were observed. A pseudocontact shift mechanism accounts for the majority of the observed proton induced shifts. However, significant contact shift contributions are required in order to account for the direction and magnitude of several of the observed 31P induced shifts. Several of the commercially available LSRs are not suitable for use in obtaining induced 31P shifts due to broadening of the signal into the baseline. In terms of both the magnitude of the induced proton and 31p shifts and line broadening, Yb(fod) 3 and Pr(fod) 3 appear to be the best general shift reagents for organophosphorus substrates.

Properties and Interactions of Lanthanides: Interactions with External Fields

The values of the diamagnetic susceptibilities and nuclear magnetic shielding constants, calculated from numerical Hartree–Fock functions, are reported for the neutral atoms and the first three positive ions of the lanthanides.

The interaction of lanthanide and nitrate ions in solution — II: The relative interaction strength with water and nitrate in organic solvents

The competition of water, nitrate ions and solvent for interaction with lanthanide ions has been studied by measuring the absorption spectra of solutions containing suitable combinations of these components. The role of the water in lanthanide nitrate extracts by TBP and by a tri-alkylammonium nitrate solution has also been studied. The following affinity series of ligands and solvents for lanthanide ions has been obtained: DMF> TBP > NO 3−∼ H 2 O > EtOH > dioxane

Interaction of lanthanide and nitrate ions in solutions. I. Inner- and outer-sphere coordination in aqueous solutions

Interaction of lanthanide and nitrate ions in solutions. I. Inner- and outer-sphere coordination in aqueous solutions