Ligand-exchange kinetics and solution equilibriums of cadmium, zinc, and lead nitrilotriacetate complexes

Rabenstein, Dallas L.; Kula, Richard J.

doi:10.1021/ja01038a017

Cited by 61 publications

(45 citation statements)

References 4 publications

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“…Before discussing the UV-visible spectra of the colored complexes of divalent Cu, Ni & Co it should be noted that upon dissolution in water the tetrahedral complexes add two water molecules in cis-position to give an octahedral structure [4].…”

Section: Resultsmentioning

confidence: 99%

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Studies On Some Acid Divalent-Metal Nitrilotriacetate Complexes

et al. 2000

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Section: Resultsmentioning

confidence: 99%

“…Rabenstien and Kula [4] 3-to be due to the fact that a rate limiting proton transfer step from nitrogen in [HNTA] 2-must occur before complex formation takes place.…”

Section: Introductionmentioning

confidence: 99%

Studies On Some Acid Divalent-Metal Nitrilotriacetate Complexes

et al. 2000

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“…Equilibrium studies of Cu(I1)-NTA complex formation have been made (1)(2)(3)(4)(5), and Whitlow (6) has determined the crystal and molecular structure of sodium nitrilotriacetatocopper(I1) monohydrate by single-crystal X-ray analysis. Rabenstein and co-workers (7,8) have studied by nuclear magnetic resonance the ligand-exchange kinetics and solution equilibria of cadmium, zinc, and lead nitrilotriacetic acid complexes with special attention to the state of protonation of the ligand; in the case of copper it was of interest to examine the kinetics of the Cu(II)-NTA reaction.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of the Cu(II) – Nitrilotriacetic Acid Reaction

Maguire¹

1974

Can. J. Chem.

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The kinetics of the reaction between Cu(II) and nitrilotriacetic acid (NTA) to form the 1:1 complex have been studied by the stopped-flow technique over the pH range 2–6. The reaction is kinetically first order in both [Cu(II)] and [NTA]total; the rate constant has a minimum value of 1.1 × 105 l mol−1 s−1 in the pH range 3.5–5 and increases with either increasing or decreasing pH. An explanation for the observed kinetic behavior may be that in the case of the monoprotonated species HNTA2− there is a rate-limiting transfer of a proton from nitrogen before complex formation takes place, and that this transfer is facilitated with increasing acidity.

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“…While 2:1 [Zn(NTA) 2 ] 4− complexes can form under certain conditions, the affinity data suggests the 1:1 complex will dominate in the absence of excess ligand. [30] To assess the photoactivity of NTAdeCage and the corresponding metal complexes, the compounds were exposed to 365 nm light (3 Wcm −2 ) (Figure 3) and the photoreaction was analyzed by LCMS and GCMS. After irradiating a 1.12 mM solution of NTAdeCage (40 mM HEPES, 100 mM KCl, pH 7.5) a new peak appears in the LC trace that corresponds to a compound with m/z 151.0 (measured by GCMS) with a concomitant decrease in the LC peak corresponding to NTAdeCage (RF = 1.7, 254 nm, m/z 312.0).…”

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A Zinc(II) Photocage Based on a Decarboxylation Metal Ion Release Mechanism for Investigating Homeostasis and Biological Signaling

et al. 2015

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Metal ion signaling in biology has been studied extensively with ortho-nitrobenzyl photocages; however, the low quantum yields and other optical properties are not ideal for these applications. We describe the synthesis and characterization of NTAdeCage, the first member in a new class of Zn 2+ photocages that utilizes a light-driven decarboxylation reaction in the metal ion release mechanism. NTAdeCage binds Zn 2+ with sub-pM affinity using a modified nitrilotriacetate chelator and exhibits an almost 6 order of magnitude decrease in metal binding affinity upon uncaging. In contrast to other metal ion photocages, NTAdeCage and the corresponding Zn 2+ complex undergo efficient photolysis with quantum yields approaching 30%. The ability of NTAdeCage to mediate the uptake of 65 Zn 2+ by Xenopus laevis oocytes expressing hZIP4 demonstrates the viability of this photocaging strategy to execute biological assays. Keywords cage compounds; coordination compounds; photolysis; X-ray diffraction; zinc The importance of Zn 2+ beyond structural and catalytic functions in proteins has become increasingly apparent. [1] Zinc and iron regulated proteins (ZIPs) increase cytosolic Zn 2+ concentrations; in contrast, zinc transporter (ZnT) proteins decrease cytosolic Zn 2+ . [2,3] Elucidating the function of free or loosely bound Zn 2+ in the cytosol as well as in intracellular compartments remains important; however, the ability to modulate Zn 2+ levels in vivo in a time-resolved manner remains elusive. [4] Free Zn 2+ has been implicated in various signaling pathways, [1] and recently fertilization of oocytes has been shown to trigger "zinc sparks" that serve to initiate meiosis at the beginning stages of embryotic development. [5] The development of new methodologies to simulate fluctuations in Zn 2+ concentrations in a spatiotemporal manner would facilitate the understanding of complex signaling processes.Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/anie.201505778. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptThe photochemistry of ortho-nitrobenzyl (oNB) chromophores initially was recognized as a means to deliver Ca 2+ in a controlled manner to biological receptors using light. [6] We subsequently adapted two Ca 2+ -releasing strategies to develop photocaged complexes for biologically relevant metal ions such as Zn 2+ , Cu + and Fe 3+ . [7,8] In the Cast photocages, decreased electron density on a coordinated aniline nitrogen atom following photolysis lowers chelator binding affinity. [9][10][11] While this strategy can adequately buffer Ca 2+ at typical intracellular resting levels (ca. 100 nM) and simulate biologically relevant concentration increases, [6,12] the reliance on weakly coordinating aniline-based ligands precludes use with Zn 2+ , which experiences tighter intracellular homeostasis. [11] Alternatively, photolytically breaking a carbon-heteroatom bond provides compounds that release metal ions through the reduction ...

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Ligand-exchange kinetics and solution equilibriums of cadmium, zinc, and lead nitrilotriacetate complexes

Cited by 61 publications

References 4 publications

Studies On Some Acid Divalent-Metal Nitrilotriacetate Complexes

Studies On Some Acid Divalent-Metal Nitrilotriacetate Complexes

Kinetics of the Cu(II) – Nitrilotriacetic Acid Reaction

A Zinc(II) Photocage Based on a Decarboxylation Metal Ion Release Mechanism for Investigating Homeostasis and Biological Signaling

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