Lanthanide Complexes as Nuclear Magnetic Resonance Structural Probes: Paramagnetic Anisotropy of Shift Reagent Adducts

Horrocks, William DeW.; Sipe, James P.

doi:10.1126/science.177.4053.994

Cited by 88 publications

(18 citation statements)

References 18 publications

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“…f Accurate determination of Pi/2 and A were precluded by overlap with the residual water signal; however, the approximate values given are consistent with values obtained by extrapolation from lower [Dy]. g The poor correlation with A has been noted before (12), and ascribed to the large axial: equatorial geometric factor ratio in Tm(dipivaloylmethanato)3(4-picoline)2. The observed relative ATm of 3.7 correlates well with actual relative isotropic NMR shifts observed in organic, ATm -3.8 (12), and aqueous, ATm -4.6 (13), solvents.…”

Section: Methodssupporting

confidence: 62%

“…g The poor correlation with A has been noted before (12), and ascribed to the large axial: equatorial geometric factor ratio in Tm(dipivaloylmethanato)3(4-picoline)2. The observed relative ATm of 3.7 correlates well with actual relative isotropic NMR shifts observed in organic, ATm -3.8 (12), and aqueous, ATm -4.6 (13), solvents. h P1/, of unresolved inner and outer (-NMe3).…”

Section: Methodsmentioning

confidence: 99%

“…however, their use in obtaining structural information has been a subject of some controversy (12,(15)(16)(17)(18)(19)(20)(21)(22) (13).…”

Section: Origin and Utility Of The Isotropic Nmr Shiftmentioning

confidence: 99%

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Lanthanide Ion-Induced Isotropic Shifts and Broadening for Nuclear Magnetic Resonance Structural Analysis of Model Membranes

Andrews

Faller

Gilliam

et al. 1973

Proc. Natl. Acad. Sci. U.S.A.

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The effects of a series of aquated lanthanide ions on the nuclear magnetic resonance spectrum of phospholipid bilayer suspensions are reported. The ability of these ions to provide a spectral distinction between morphologically exterior resonances and their interior counterparts was confirmed. Measurements of the relative shifting and broadening capabilities of these ions are reported, and their correlation with solid-state magnetic susceptibility anisotropies is shown to implicate a dipolar (pseudocontact) mechanism as the source of this effect. The potential for the use of dipolar shifts as structural probes is discussed and an alternative method using dipolar shifting and broadening reagents simultaneously is presented.The use of nuclear magnetic resonance spectroscopy (NMR) as a tool for the study of artificial phospholipid bilayers (a model membrane system), as well as biological membranes themselves, has been of great current interest. Recently, Bystrov et al. (1) reported the 1H NMR spectrum of a phospholipid bilayer in the presence of aquated Eu+3 ions, in which they observed an upfield shift of a portion of the N-methyl choline resonance, which originally had been a strong singlet in the absence of Eu+3. A dependence of the magnitude of the shift on the concentration of europium was also noted. These workers advanced the explanation that this metal ion, by coordination to the exterior phosphate head groups, was capable of lifting the accidental chemical shift equivalence of the protons on the inside and outside of the closed bilayers. The spectral result was thus two singlets, corresponding to the (-NMe3) i and (-NMe3), groups. Presumably, the outer protons experienced an isotropic shift due to the paramagnetic ion and the inner protons remained unshifted. Other reagents that induce spectral modifications of this kind have been reported and include small chemical shifts induced through the agency of anions (2, 3) and elemental iodine (2), and broadening of resonances by the paramagnetic Mn+2 and Gd+3 ions (1, 3, 4).It is evident that a technique capable of deriving quantitative information on the molecular disposition of membrane components would be of great value, and the reagents described above are potentially useful in this context. This apAbbreviations: (-X-)i and (-X-)0, resonance assignments for those portions of an NMR (nuclear magnetic resonance) signal arising from chemically similar but spatially distinct nuclei residing on the inside and outside of a closed bilayer, respectively; Ln +3, a generic, trivalent lanthanide ion; a, isotropic chemical shift in ppm relative to the unshifted portion of the same resonance; vP/2, full observed resonance width at half-height; V1/2', full corrected width at half-height, i.e., V1/2 (observed) -vl/2 (natural).pears to be particularly true of the Eu+3 ion, by virtue of the larger changes involved. Thus, in connection with the problem of site-labeling of membrane constituents, we sought to investigate the utility of lanthanide ions as structural prob...

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Section: Methodssupporting

confidence: 62%

Section: Methodsmentioning

confidence: 99%

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Lanthanide Ion-Induced Isotropic Shifts and Broadening for Nuclear Magnetic Resonance Structural Analysis of Model Membranes

Andrews

Faller

Gilliam

et al. 1973

Proc. Natl. Acad. Sci. U.S.A.

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“…It is not surprising that the direction of the shifts and the relative ordering is nearly the same as the shifts of a substrate recorded in the presence of the shift reagent [Ln(dpm) 3 ], where the shifts also result mainly from the pseudocontact mechanism. [24] Ligand -4] showed the kinetic inertness towards ligand exchange in methanol. [16] On the other hand, vanadylcontaining metallacrown complexes [9-MC (VO)N(shi) -3] and [9-MC (VO)N(nha) -3], unable to sequester metal ions in their cavities, were found to be kinetically labile in methanol.…”

Section: Nmr Analysis Of Ln(no 3 ) 3 [15-mc Cumentioning

confidence: 99%

Lanthanide(III)‐Induced Conversion of 12‐Metallacrown‐4 to 5‐Metallacrown‐5 Complexes in Solution

et al. 2005

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The conversion of 12-metallacrown-4 complexes with copper(II) in the central cavity to 15-metallacrown-5 complexes with lanthanide(III) ions in the central cavity upon addition of trivalent lanthanide ions was analysed in solution by electrospray ionisation mass spectrometry (ESI-MS), absorption spectrophotometry, circular dichroism and proton NMR spectroscopy. In all cases, copper(II) ions were the ring metals. The lanthanide-induced shifts of the proton resonances in the NMR spectra of different lanthanide(III)-containing 15-metallacrown-5 complexes with tyrosinehydroximate ligands

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“…LIS values generally arise from a combination of the Fermi contact and dipolar or pseudo-contact interactions, which can be conveniently expressed as follows for a complex with effective axial symmetry (threefold or higher) [1,3,12]:…”

Section: Introductionmentioning

confidence: 99%

Analysis of lanthanide induced NMR shifts using a crystal field independent method: application to complexes of tetraazamacrocyclic ligands

Ren

Zhang

Sherry

et al. 2002

Inorganica Chimica Acta

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The linear graphical analysis of the LIS NMR data available for the axially symmetric complexes [Ln(DOTA)] ( (M and m isomers), [Ln(DOTP)] 5( (pH 10.0, 7.0 and 3) and [Ln(DOTEA)] 3' using the classical crystal field dependent method and a crystal field independent method were compared. As the second method provides ratios of geometric structural terms G rather than G values, the effect of lanthanide contraction was reduced. Thus, the large breaks in plots observed for all nuclei of those systems using the classical method are still present in the plots of the second method, only in a few of the nuclei and much reduced. This shows that the large breaks at the middle of the lanthanide series present in plots of the classical method as well as the anomalies often present for those plots for the Tm and Yb ions are mostly due to changes of the crystal field coefficient A 2 0 r 2 along the lanthanide series, while both the hyperfine coupling constants and the ratios of geometric terms also change as a result of the lanthanide contraction, leading to small breaks at the middle of the lanthanide series. Analysis of the proton shifts of [Ln(DOTP)] complexes at pH 10, 7 and 3 indicates that protonation of the complexes results in a decrease on the crystal field coefficient. The dipolar shift ratios and absolute shifts obtained were also interpreted in terms of the structural models for those complexes in solution and their available Xray crystal structures. #

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Lanthanide Complexes as Nuclear Magnetic Resonance Structural Probes: Paramagnetic Anisotropy of Shift Reagent Adducts

Cited by 88 publications

References 18 publications

Lanthanide Ion-Induced Isotropic Shifts and Broadening for Nuclear Magnetic Resonance Structural Analysis of Model Membranes

Lanthanide Ion-Induced Isotropic Shifts and Broadening for Nuclear Magnetic Resonance Structural Analysis of Model Membranes

Lanthanide(III)‐Induced Conversion of 12‐Metallacrown‐4 to 5‐Metallacrown‐5 Complexes in Solution

Analysis of lanthanide induced NMR shifts using a crystal field independent method: application to complexes of tetraazamacrocyclic ligands

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