Copper-histidine ternary complex equilibria with glutamine, asparagine and serine. The implications for computer-simulated distributions of copper(II) in blood plasma

Berthon, Guy; Hacht, Brahim; Blais, Marie-José; May, Peter M.

doi:10.1016/s0020-1693(00)81215-3

Cited by 59 publications

(17 citation statements)

References 39 publications

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“…Thus the presence of either deprotonated or hydroxocomplexes (or both) is indicated. In addition, these curves do not present marked plateau around p p ¼ 1 or 2 which are usually observed respectively for mononuclear species ML and ML 2 in the case of strong ligands (Berthon et al, 1986). In addition, the ''tails'' displayed by the experimental curves are regarded as specific to the formation of hydroxo species.…”

Section: Aluminium(iii) -Acetate Equilibriummentioning

confidence: 74%

Speciation studies of aluminium(III)–acetate complexes under physiological conditions

Hacht¹

2008

Chemical Speciation & Bioavailability

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The aluminium complexes of acetic acid (ACT) have been studied using potentiometric titrations under physiological conditions of temperature (37 C) and ionic strength (0.15 mol dm À 3 NaCl) and at different ligand to metal ratios. The variations of pH were measured with the help of a glass electrode calibrated daily in hydrogen ion concentrations. Results obtained within the pH range of 2.6 -4.2 were analysed to determine stability constants using the SUPERQUAD program. Different complex combinations were considered during the calculation procedure, and evidence was found for ML 2 mononuclear species beside binuclear hydroxo-complexes M 2 L(OH) 2 and M 2 L(OH) 3 and metal ion hydroxides. Speciation calculations based on the corresponding constants were then used to simulate species distributions.

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Section: Aluminium(iii) -Acetate Equilibriummentioning

confidence: 74%

Speciation studies of aluminium(III)–acetate complexes under physiological conditions

Hacht¹

2008

Chemical Speciation & Bioavailability

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“…[14,15] Simplified models were proposed to predict the concentration of the free Gd 3 + in blood plasma in the presence of gadolinium-based MRI contrast agents. [16,17,18] For such equilibrium calculations, it is necessary to know the protonation constants of the ligand, and the composition of the complexes participating in the equilibria, as well as their protonation and stability constants.…”

Section: Resultsmentioning

confidence: 99%

“…The results of our kinetic studies, however, show that the importance of the metal-assisted dissociation for [GdA C H T U N G T R E N N U N G (AAZTA)] À is very low and, at the low Cu 2 + and Zn 2 + concentrations indicated above, their contribution is negligible (the importance of the Zn 2 + -assisted transmetalation is generally lower than the Cu 2 + assisted one [25,26] ). By taking into account these considerations, for the reaction of [GdA C H T U N G T R E N N U N G (AAZTA)] À , the terms k Table 3, and also for [GdA C H T U N G T R E N N U N G (DTPA)] 2À , with the use of Equation (15), are shown in Table 4. By using the k (Table 4).…”

Section: H T U N G T R E N N U N G (Aazta)]mentioning

confidence: 99%

Equilibrium and Kinetic Properties of the Lanthanoids(III) and Various Divalent Metal Complexes of the Heptadentate Ligand AAZTA

Baranyai

Uggeri

Giovenzana

et al. 2009

Chemistry A European J

127

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The heptadentate ligand 1,4-bis(hydroxycarbonylmethyl)-6-[bis(hydroxycarbonylmethyl)]amino-6-methylperhydro-1,4-diazepine (AAZTA) and its derivatives were recently reported to give stable complexes with Gd(3+) with superior efficiency as MRI contrast agents. Nevertheless, only preliminary data are available on the coordination behavior of this interesting ligand. In this work, thermodynamic and kinetic stability data are determined for the formation of complexes with AAZTA and the lanthanoid metal ions, and other divalent metal ions of interest for this application. The AAZTA ligand binds the lanthanoid ions with log K(ML) values of 17.53-21.85 with its affinity steadily increasing from La(3+) to Lu(3+), suggesting that the seven-membered skeleton is better suited to accommodate smaller metal ions. Even though the denticity is lower, the stability of the heavier lanthanoid complexes is comparable to those of the classical ligand diethylenetriaminepentaacetic acid (DTPA). The transmetalation reactions of [Gd(AAZTA)](-) with Cu(2+) and Eu(3+) predominantly occur through proton-assisted dissociation of the complex. The role of the direct attack of Cu(2+) or Eu(3+) in the exchange reactions is limited, although the formation of dinuclear complexes decreases the proton-assisted dissociation. Near physiological conditions, [Gd(AAZTA)](-) is significantly more inert than [Gd(DTPA)](2-), allowing its potentially safe use as contrast agent in magnetic resonance imaging.

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“…Binding constants have been measured for a variety of Cu(His)(L) complexes [104][105][106][107][108]. There is very little selectivity among the α amino acids for binding as the bidentate L ligand in the Cu(His)(L) complexes.…”

Section: Copper Speciationmentioning

confidence: 99%

A speciation model of essential trace metal ions in phloem

Harris

Sammons

Grabiak

2012

Journal of Inorganic Biochemistry

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Copper-histidine ternary complex equilibria with glutamine, asparagine and serine. The implications for computer-simulated distributions of copper(II) in blood plasma

Cited by 59 publications

References 39 publications

Speciation studies of aluminium(III)–acetate complexes under physiological conditions

Speciation studies of aluminium(III)–acetate complexes under physiological conditions

Equilibrium and Kinetic Properties of the Lanthanoids(III) and Various Divalent Metal Complexes of the Heptadentate Ligand AAZTA

A speciation model of essential trace metal ions in phloem

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