An LC method for measuring complex formation equilibria by competitive chelation

Chellquist, Eric M.; Searle, Roger

doi:10.1016/0731-7085(93)80059-a

Cited by 7 publications

(6 citation statements)

References 9 publications

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“…64 PyMTA forms highly stable complexes with Gd(III) (log K ∼ 19). 58,65 The Michael addition of the thiol group of the cysteine residue to the vinyl group of the 4-vinyl-PyMTA (3) results in a thioether linkage that we expected to be stable in the cellular environment.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…4-Vinyl-PyMTA ( 3 ) was recently introduced by Yang et al as a tag in site-specific labeling of proteins with lanthanides for structure analysis with NMR-spectroscopic experiments . PyMTA forms highly stable complexes with Gd(III) (log K ∼ 19). , The Michael addition of the thiol group of the cysteine residue to the vinyl group of the 4-vinyl-PyMTA ( 3 ) results in a thioether linkage that we expected to be stable in the cellular environment.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Gd(III) complexes also caught our interest because we expected the Gd(III) ion to withstand the reducing conditions inside a cell. Although Gd(III) is highly toxic, its toxicity is significantly reduced upon complexation. ,− Indeed, as shown below, experiments proved the complex Gd-PyMTA to be inert in the cell extract of Xenopus laevis oocytes for at least 24 h at 18 °C and the morphology of Xenopus laevis oocytes that had been loaded with Gd-PyMTA labeled molecules to stay unchanged for at least 3 h at 18 °C. To further explore the applicability of Gd(III) complexes for in-cell DEER measurements, the proline rich peptide H-AP 10 CP 10 CP 10 -NH 2 (peptide 7 ) was labeled with the Gd(III) complex Gd-PyMTA, using the two thiol groups of the peptide as covalent anchors and the decaproline segment as a spacer.…”

Section: Introductionmentioning

confidence: 92%

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Gd(III)-PyMTA Label Is Suitable for In-Cell EPR

et al. 2014

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Distance measurement in the nanometer range by electron paramagnetic resonance spectroscopy (EPR) in combination with site-directed spin labeling is a very powerful tool to monitor the structure and dynamics of biomacromolecules in their natural environment. However, in-cell application is hampered by the short lifetime of the commonly used nitroxide spin labels in the reducing milieu inside a cell. Here, we demonstrate that the Gd(III) based spin label Gd-PyMTA is suitable for in-cell EPR. Gd-PyMTA turned out to be cell compatible and was proven to be inert in in-cell extracts of Xenopus laevis oocytes at 18 °C for more than 24 h. The proline rich peptide H-AP10CP10CP10-NH2 was site-directedly spin labeled with Gd-PyMTA at both cysteine moieties. The resulting peptide, H-AP10C(Gd-PyMTA)P10C(Gd-PyMTA)P10-NH2, as well as the model compound Gd-spacer-Gd, which consists of a spacer of well-known stiffness, were microinjected into Xenopus laevis oocytes, and the Gd(III)-Gd(III) distances were determined by double electron-electron resonance (DEER) spectroscopy. To analyze the intracellular peptide conformation, a rotamer library was set up to take the conformational flexibility of the tether between the Gd(III) ion and the Cα of the cysteine moiety into account. The results suggest that the spin labeled peptide H-AP10C(Gd-PyMTA)P10C(Gd-PyMTA)P10-NH2 is inserted into cell membranes, coinciding with a conformational change of the oligoproline from a PPII into a PPI helix.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

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Gd(III)-PyMTA Label Is Suitable for In-Cell EPR

et al. 2014

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“…[1][2][3][4][5][6][7][8][9] Moreover, one study describes the separation of lutetium and gadolinium-polyazaaromatic complexes for diagnostic agents metabolic studies. 10 Reversed phase (RP-HPLC) 2,4,[6][7][8]10 and ion pairing chromatography (IP-HPLC) 1,3,5,9 have been mainly used for such investigations, while ion exchange, 11 size exclusion 3,12 and affinity 13 chromatography have also been used, but to a much lesser extent. In these studies, RP-HPLC and IP-HPLC were usually coupled with uorescence and UV-vis spectrometers, with derivatisation steps oen needed for UV-vis detection of lanthanide species, while the coupling of RP-HPLC with ESI-MS or elemental based detection, such as inductively coupled plasma optical emission spectrometry (ICP-OES), 2,6,7 was much less common.…”

Section: Introductionmentioning

confidence: 99%

Simple separation and characterization of lanthanide–polyaminocarboxylic acid complexes by HILIC ESI-MS

et al. 2015

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“…For Eu(III) chelates, this hydration sphere does not impair the luminescence efficiency which remains competitive with that of some Eu(III)-based commercial luminescent probes. Moreover, these complexes are characterized by an attractive stability in aqueous solutions at physiological pH (log K cond Gd = 16.4, log K cond Eu = 16.6, pH 7.3) (9). These values are in the range of those of Gd(III) chelates used in clinical practice; a similar conditional stability constant [log K cond = 14.9 pH 7.4 ( 10)] has been established for Gd-DTPA-BMA (Omniscan®).…”

Section: Introductionmentioning

confidence: 99%

Bifunctional Gd(III) and Tb(III) chelates based on a pyridine–bis(iminodiacetate) platform, suitable optical probes and contrast agents for magnetic resonance imaging

Laurent

Elst

Galaup

et al. 2014

Contrast Media & Molecular

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To study the physicochemical properties of lanthanide complexes derived from a bifunctional chelating agent based on a PMN-tetraacetic acid moiety {PMN-tetraacetic acid (1): [2,6-pyridinediylbis(methylene nitrilo)-tetraacetic acid]}, 4-carboxylic acid substituted pyridine derivative (2) was synthesized. This ligand forms heptadentate (N3 O4 ) Ln(III) complexes (Ln = Gd, Eu, Tb), with two water molecules completing the inner coordination sphere of the metal. The parameters that govern the relaxivity of the Gd(III) complex and the luminescence of Eu(III) and Tb(III) complexes were obtained by (17) O and (1) H NMR studies and time-resolved fluorescence experiments, respectively. The gadolinium and terbium complexes show interesting properties either for MRI or FOR optical imaging; that is, for the Gd complex, a high proton relaxivity (r1 = 6.4 s(-1) mM(-1) at 20 MHz) with short water residence time (τM = 38.5 ns); for the Tb complex, a luminescence lifetime of 1.22 ms at room temperature and a luminescence quantum yield of 10%. The kinetic stability of these complexes toward blood protein, cation or bioactive oxyanion was also examined. The Gd(2)(H2O)2 complex does not interact with human serum albumin, but undergoes a transmetalation reaction with Zn(II) in a phosphate buffer solution (pH 7.4), rather similar to that of Gd-DTPA-BMA(H2 O). On the other hand, as observed for Eu and Tb complexes, these chelates do not form ternary complexes with bidentate anions such as l-lactate, citrate or carbonate. Finally, a phosphatidylserine-specific hexapeptide (TLVSSL) was grafted on Gd or Tb chelates, and the Gd-peptide conjugate was used in vitro for targeting apoptotic cells.

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An LC method for measuring complex formation equilibria by competitive chelation

Cited by 7 publications

References 9 publications

Gd(III)-PyMTA Label Is Suitable for In-Cell EPR

Gd(III)-PyMTA Label Is Suitable for In-Cell EPR

Simple separation and characterization of lanthanide–polyaminocarboxylic acid complexes by HILIC ESI-MS

Bifunctional Gd(III) and Tb(III) chelates based on a pyridine–bis(iminodiacetate) platform, suitable optical probes and contrast agents for magnetic resonance imaging

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