Critical Stability Constants

Martell, Arthur E.; Smith, Robert M.

doi:10.1007/978-1-4615-6761-5

Cited by 1,760 publications

(664 citation statements)

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“…The reduction of adsorption of REEs followed the orders: citric acid > malic acid > tartaric acid > acetic acid. This order is in consist with the stability constants of REEs with these organic ligands (log K 1 for four Laorganic acid complexes, Martell and Smith, 1977), indicating the formation of aqueous REEs-organic ligands complexes is one of the important reasons for the adsorption decrease. In the absence of organic ligands system with only electrostatic attraction and repulsion existing, the adsorption of REEs was a function of soil characteristics, while in the presence of organic ligands, there existed a competitive effect for REEs between soil adsorption sites and aqueous organic ligands.…”

Section: Effect Of Organic Acids and Ph On Adsorption Of Rees By Soilsmentioning

confidence: 78%

Effect of organic acids on adsorption and desorption of rare earth elements

2002

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Section: Effect Of Organic Acids and Ph On Adsorption Of Rees By Soilsmentioning

confidence: 78%

Effect of organic acids on adsorption and desorption of rare earth elements

2002

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“…When pH increased, major forms of citric acid changed from H 3 L, H 2 L À , and HL 2À to L 3À . HL 2À and L 3À always showed greater chelating ability with heavy metals than H 3 L and H 2 L À (Martell and Smith, 1977), leading to larger desorption amounts of Cu, Cd, and Pb in the presence of HL 2À and L 3À than in the presence of H 3 L and H 2 L À . The strong tendency of complex formation induced the increase in metal desorption as pH increased from 3.1 to 6.…”

Section: Effects Of Lmwoas and Initial Ph On Desorption Of Cu CD Anmentioning

confidence: 94%

“…So did malic acid in the case of desorbing Cd and Pb. When it comes to Cu, the complexing ability of Cu with malic acid is somewhat higher than those of Cd and Pb (Martell and Smith, 1977). When Cu was desorbed by malic acid, the pH effect on desorption due to increase in ligand species and quantity prevailed over that due to increase in soil negative charge and metal hydrolysis.…”

Section: Effects Of Lmwoas and Initial Ph On Desorption Of Cu CD Anmentioning

confidence: 98%

“…In order to investigate the effect of LMWOAs on pHdependent adsorption citric acid and Pb were chosen as an example as citric acid has the highest complex stability (Martell and Smith, 1977). Twenty milliliters of 0.01 mol l À1 citric acid (0.01 mol l À1 NaNO 3 as background electrolyte) was added to 0.500 g soil.…”

Section: Adsorption Of Cu CD and Pb As A Function Of Phmentioning

confidence: 99%

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Effects of low-molecular-weight organic acids and residence time on desorption of Cu, Cd, and Pb from soils

2004

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“…First, the increase in the stability of the complex upon freezing is in the range expected for the enthalpy change due to metal-ligand binding. For example, the enthalpy change for binding of Mn 2+ to two histidines is -5.2 kcal/mol (22). A change in temperature from 25 °C to 0 °C will increase the stability of the complex by a factor of 2.…”

Section: Epr Spectroscopymentioning

confidence: 99%

Metal Binding Studies and EPR Spectroscopy of the Manganese Transport Regulator MntR

et al. 2006

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Manganese transport regulator (MntR) is a member of the diphtheria toxin repressor (DtxR) family of transcription factors that is responsible for manganese homeostasis in [4295][4296][4297][4298][4299][4300][4301][4302][4303], and generally follow the Irving-Williams series. Direct detection of the dinuclear Mn 2+ site in MntR with EPR spectroscopy is presented, and the exchange interaction was determined, J = -0.2 cm -1 . This value is lower in magnitude than most known dinuclear Mn 2+ sites in proteins and synthetic complexes and is consistent with a dinuclear Mn 2+ site with a longer Mn···Mn distance (4.4 Å) observed in some of the available crystal structures. MntR is found to have a surprisingly low binding affinity (∼160 μM) for its cognate metal ion Mn 2+ . Moreover, the results of DNA binding studies in the presence of limiting metal ion concentrations were found to be consistent with the measured metal-binding constants. The metalbinding affinities of MntR reported here help to elucidate the regulatory mechanism of this metaldependent transcription factor.Bacteria handle the delicate issue of metal ion homeostasis using a class of transcription factors known as metalloregulatory proteins (metalloregulators). In some systems, these metal-sensing proteins are involved in mediating the removal of toxic metals, while in other systems they are central to maintaining the required levels of essential metals. To date, a large number of metalloregulatory proteins have been identified that respond to a variety of metal ions (1-3). The subject of how metal binding is translated into an ability to control transcription via a † This work was supported by the University of California, San Diego, the Hellman Family fund, a Cottrell Scholar Award from the Research Corporation (S.M.C.), and the National Institutes of Health GM077387 (M.P.H.). * Author to whom correspondence should be adddressed. (M.P.H.) Telephone: (412) 268-1058; fax: (412) NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript metalloregulator has become a prominent subject of investigation (4-10). Indeed, many metalloregulators are reported to bind several metal ions in vitro, while only eliciting a specific transcriptional response when they are bound to the cognate metal in vivo (5)(6)(7)9). This observation naturally leads to the question: how does a metalloregulator selectively respond to its cognate metal ion as opposed to other available metal ion activators? The ability of a metalloregulator to respond selectively to a metal ion may depend on several factors, including the availability of the requisite metal ion, the binding affinity for the metal ion, the charge on the metal ion, and the coordination geometry/number assumed by the metal ion upon binding. Determining which of these factors are most important for a given metalloregulator is essential for gaining a better understanding of how these proteins elicit transcriptional control.The manganese transport regulator MntR 1 is found in Bacillus subtilis and is ...

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Critical Stability Constants

Cited by 1,760 publications

References 0 publications

Effect of organic acids on adsorption and desorption of rare earth elements

Effect of organic acids on adsorption and desorption of rare earth elements

Effects of low-molecular-weight organic acids and residence time on desorption of Cu, Cd, and Pb from soils

Metal Binding Studies and EPR Spectroscopy of the Manganese Transport Regulator MntR

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