Stability constants for complexes of the siderophore desferrioxamine B with selected heavy metal cations

Hernlem, Bradley J.; Vane, Leland M.; Sayles, Gregory D.

doi:10.1016/0020-1693(95)04780-8

Cited by 146 publications

(131 citation statements)

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“…However, they were unable to determine the pK a of HMSA, which they believed to be 1.92 from the NIST database (Martell et al, 2004) but found to be certainly <0.9. Christenson and Schijf (2011) pointed out that the NIST database contains a sign error and that the actual value is −1.92 (Covington and Thompson, 1974), congruent with the observation of Hernlem et al (1996). Because of this extremely low pK a value, metal-MSA complexes do not dissociate within our experimental pH window (∼2-11) and their stability constants cannot be directly determined by potentiometric titration.…”

Section: Stability Constants Of Mg−msa and Ca−msa Complexesmentioning

confidence: 61%

“…Although their potentiometric data appears to be of excellent quality, these authors routinely include in their regression models a stability constant for metal complexes with fully deprotonated DFOB, implying coordination of the metal cation with the DFOB terminal amine. However, while such a complex may exist for some tetravalent cations like Sn 4+ (Hernlem et al, 1996) and Hf 4+ (Yoshida et al, 2004), it has not been found for other highly charged cations like Th 4+ (Whisenhunt et al, 1996) or the trivalent lanthanides (Christenson and Schijf, 2011) and is very unlikely to form with Mg 2+ and Ca 2+ . Schijf et al (2015) emphasized that adding this extra degree of freedom to the regression model can lead to under-constrained fits and probably explains why Farkas et al (1999) were unable to resolve values for log L β 1 , whereas the bidentate DFOB complex, analogous to the bidentate AH complex (Table 5), is certainly expected to form as the first of three equivalent steps leading to the stable hexadentate DFOB complex.…”

Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 99%

“…Its protonated form is methanesulfonic acid, or HMSA ( Figure 1B). Hernlem et al (1996) noted that the inevitable presence in DFOB solutions of an equal amount of MSA − could lead to a bias in potentiometric titrations if the latter forms fairly stable complexes with the analyte metal. However, they were unable to determine the pK a of HMSA, which they believed to be 1.92 from the NIST database (Martell et al, 2004) but found to be certainly <0.9.…”

Section: Stability Constants Of Mg−msa and Ca−msa Complexesmentioning

confidence: 99%

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Determination of the Side-Reaction Coefficient of Desferrioxamine B in Trace-Metal-Free Seawater

Schijf

Burns

2016

Front. Mar. Sci.

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Electrochemical techniques like adsorptive cathodic stripping voltammetry with competitive ligand equilibration (ACSV-CLE) can determine total concentrations of marine organic ligands and their conditional binding constants for specific metals, but cannot identify them. Individual organic ligands, isolated from microbial cultures or biosynthesized through genomics, can be structurally characterized via NMR and tandem MS analysis, but this is tedious and time-consuming. A complementary approach is to compare known properties of natural ligands, particularly their conditional binding constants, with those of model organic ligands, measured under suitable conditions. Such comparisons cannot be meaningfully interpreted unless the side-reaction coefficient (SRC) of the model ligand in seawater is thoroughly evaluated. We conducted series of potentiometric titrations, in non-coordinating medium at seawater ionic strength (0.7 M NaClO 4 ) over a range of metal:ligand molar ratios, to study complexation of the siderophore desferrioxamine B (DFOB) with Mg and Ca, for which it has the highest affinity among the major seasalt cations. From similar titrations of acetohydroxamic acid in the absence and presence of methanesulfonate (mesylate), it was determined that Mg and Ca binding to this common DFOB counter-ion is not strong enough to interfere with the DFOB titrations. Stability constants were measured for all DFOB complexes with Mg and Ca including, for the first time, the bidentate complexes. No evidence was found for Mg and Ca coordination with the DFOB terminal amine. From the improved DFOB speciation, we calculated five SRCs for each of the five (de)protonated forms of DFOB in trace-metal-free seawater, yet we also present a more convenient definition of a single SRC that allows adjustment of all DFOB stability constants to seawater conditions, no matter which of these forms is selected as the "component" (reference species). An example of Cd speciation in seawater containing DFOB illustrates the non-trivial use of different SRCs for polyprotic, polydentate organic ligands.

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Section: Stability Constants Of Mg−msa and Ca−msa Complexesmentioning

confidence: 61%

Section: Calculation Of the Side-reaction Coefficient And Comparison mentioning

confidence: 99%

Section: Stability Constants Of Mg−msa and Ca−msa Complexesmentioning

confidence: 99%

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Determination of the Side-Reaction Coefficient of Desferrioxamine B in Trace-Metal-Free Seawater

Schijf

Burns

2016

Front. Mar. Sci.

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“…The same qualitative result was observed by Kraemer et al (11) in the Pb(II) adsorption edge for goethite, but the reduction in adsorbed Pb was much less than for Eu. This difference is expected, however, given the much smaller stability constant for the 1:1 complexes of DFO-B with Pb 2+ , nearly all of which are cationic species (9). Bearing in mind that goethite and boehmite dissolution are occurring during the desorption experiments, we may also conclude that DFO-B is an effective desorber of toxic metal cations from these minerals, despite its high specificity for Fe 3+ and even Al 3+ (10).…”

Section: Resultsmentioning

confidence: 87%

Adsorption of Pb(II) and Eu(III) by Oxide Minerals in the Presence of Natural and Synthetic Hydroxamate Siderophores

Kraemer

Raymond

et al. 2002

Environ. Sci. Technol.

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Trihydroxamate siderophores have been proposed for use as mediators of actinide and heavy metal mobility in contaminated subsurface zones. These microbially produced ligands, common in terrestrial and marine environments, recently have been derivatized synthetically to enhance their affinity for transuranic metal cations. However, the interactions between these synthetic derivative and adsorbed trace metals have not been characterized. In this paper we compare a natural siderophore, desferrioxamine-B (DFO-B), with its actinide-specific catecholate derivative, N-(2,3-dihydroxy-4-(methylamido)benzoyl)-desferrioxamine-B (DFOMTA), as to their effect on the adsorption of Pb(II) and Eu(III) by goethite and boehmite. In the presence of 240 µM DFO-B, a strongly depleting effect on Eu(III) adsorption by goethite and boehmite occurred above pH 6. By contrast, almost total removal of Eu(III) from solution in the neutral to slightly acidic pH range was observed in the presence of either 10 or 100 µM DFOMTA, due primarily to the formation of metal-DFOMTA precipitates. Addition of DFOMTA caused an increase in Pb(II) adsorption by goethite below pH 5, but a decrease above pH 5, such that the Pb(II) adsorption edge in the presence of DFOMTA strongly resembled the DFOMTA adsorption envelope, which showed a maximum near pH 5 and decreasing adsorption toward lower and higher pH.

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“…The conditional stability constant of desferrioxamine-B (DFB; Cheize et al, 2012;Abualhaija and van den Berg, 2014) in rain-and seawater is more than 5 orders of magnitude greater than that for other trace metals in simple electrolyte solutions [e.g., Al(III), Cu(II), Zn(II); Hernlem et al, 1996], suggesting that other metals cannot compete with binding of iron using similar siderophores. Copper and zinc complexation with HStype ligands in seawater is strong (Yang and van den Berg, 2009), and copper and iron compete for L 2 type ligands in estuarine and coastal waters (Abualhaija et al, 2015).…”

Section: Implications Of the Co-existence Of Iron-binding Ligandsmentioning

confidence: 99%

Toward a Regional Classification to Provide a More Inclusive Examination of the Ocean Biogeochemistry of Iron-Binding Ligands

2017

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Iron-binding ligands are paramount to understanding iron biogeochemistry and its potential to set the productivity and the magnitude of the biological pump in >30% of the ocean. However, the nature of these ligands is largely uncharacterized and little is known about their sources, sensitivity to photochemistry and biological transformation, or scavenging behavior. Despite many uncertainties, there is no doubt that ligands are produced by a wide range of biotic and abiotic processes, and that the bulk ligand pool encompasses a diverse range of molecules. Despite widespread recognition of the likelihood of a continuum of ligand classes making up the bulk ligand pool, studies to date largely focused on the dominant ligand. Thus, most studies have overlooked the need to assess where these targeted molecules fit across the spectrum of ligands that comprise the bulk ligand pool. Here we summarize present knowledge to critically assess the source(s), function(s), production pathways, and loss mechanisms of three important iron-binding organic ligand groups in order to assess their distinctive characteristics and how they link with observed ligand distributions. We considered that ligands are contained in broad groupings of exopolymer substances (EPS), humic substances (HS), and siderophores; using literature data for speciation modeling suggested that this adequately described the iron speciation reported in the ocean. We hypothesize that a holistic viewpoint of the multi-faceted controls on ligands dynamics is essential to begin to understand why some ligands can be expected to dominate in particular oceanic regions, depth strata, or exhibit seasonality and/or lateral gradients. We advocate that the development of a regional classification will enhance our understanding of the changing composition of the bulk ligand pool across the global ocean and to help address to what extent seasonality influences the makeup of this pool. This classification, based on selected functional ligand classes, can act as a bridge to use future ligand datasets to fill in the gaps in the continuum.

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Stability constants for complexes of the siderophore desferrioxamine B with selected heavy metal cations

Cited by 146 publications

References 9 publications

Determination of the Side-Reaction Coefficient of Desferrioxamine B in Trace-Metal-Free Seawater

Determination of the Side-Reaction Coefficient of Desferrioxamine B in Trace-Metal-Free Seawater

Adsorption of Pb(II) and Eu(III) by Oxide Minerals in the Presence of Natural and Synthetic Hydroxamate Siderophores

Toward a Regional Classification to Provide a More Inclusive Examination of the Ocean Biogeochemistry of Iron-Binding Ligands

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