Effect of ionic strength on ligand exchange kinetics between a mononuclear ferric citrate complex and siderophore desferrioxamine B

Ito, Hiroaki; Fujii, Manabu; Masago, Yoshifumi; Waite, T. David; Omura, Tatsuo

doi:10.1016/j.gca.2015.01.020

Cited by 10 publications

(17 citation statements)

References 51 publications

(76 reference statements)

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“…Although their existence in the inner core of the colloids cannot be totally ruled out, we believe it much more likely that Fe was homogeneously distributed inside the organic matter matrix. This assumption is supported by the similarity of the mean size and composition of our isolated colloids to the sizes and compositions reported for “blended” organic-Fe colloids known to comprise organically complexed Fe − (and possibly Fe-bridged entities) , rather than organic-coated Fe oxides. It is further supported by the fact that the partitioning of Fe into colloidal and soluble pools corresponded closely to the partitioning of ligands ( r 2 = 0.95, n = 16, freshwater samples only; r 2 = 0.89, n = 28, all samples): a discrepancy between the two would have been detected if part of the colloidal Fe had been a solid inorganic phase …”

Section: Discussionsupporting

confidence: 80%

Alteration of the Copper-Binding Capacity of Iron-Rich Humic Colloids during Transport from Peatland to Marine Waters

Muller

Cuscov

2017

Environ. Sci. Technol.

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Blanket bogs contain vast amounts of Sphagnum-derived organic substances which can act as powerful chelators for dissolved iron and thus enhance its export to the coastal ocean. To investigate the variations in quantity and quality of these exports, adsorptive cathodic stripping voltammetry (CSV) was used to characterize the metal binding properties of molecular weight-fractionated dissolved organic matter (MW-fractionated DOM) in the catchment and coastal plume of a small peat-draining river over a seasonal cycle. Within the plume, both iron- and copper-binding organic ligands showed a linear, conservative distribution with increasing salinity, illustrating the high stability of peatland-derived humic substances (HS). Within the catchment, humic colloids lost up to 50% of their copper-binding capacity, expressed as a molar ratio to organic carbon, after residing for 1 week or more in the main reservoir of the catchment. Immediately downstream of the reservoir, the molar ratio [L]/[C], where L was the second strongest copper-binding ligand, was 0.75 × 10 when the reservoir residence time was 5 h but 0.34 × 10 when it was 25 days. Residence time did not affect the carbon specific iron-binding capacity of the humic substances which was [L]/[C] = (0.80 ± 0.20) × 10. Our results suggest that the loss of copper-binding capacity with increasing residence time is caused by intracolloidal interactions between iron and HS during transit from peat soil to river mouth.

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Section: Discussionsupporting

confidence: 80%

Alteration of the Copper-Binding Capacity of Iron-Rich Humic Colloids during Transport from Peatland to Marine Waters

Muller

Cuscov

2017

Environ. Sci. Technol.

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“…Trivalent citrate was chosen as it had the greatest impact on forsterite carbonation in Miller et al Furthermore, citrate is a useful model organic ligand because it contains both hydroxyl and carboxyl groups and provides insight into mineral interactions with a range of naturally occurring organic matter. Although citrate is not as prevalent in the environment as simpler organic ligands, it occurs naturally in soils and subsurface waters due to biosynthesis and organic matter decomposition. − Citrate is also sometimes injected into the subsurface in engineered fluids during conventional and unconventional hydrocarbon recovery operations. , …”

Section: Introductionmentioning

confidence: 99%

Tunable Manipulation of Mineral Carbonation Kinetics in Nanoscale Water Films via Citrate Additives

Miller

Schaef

Kaszuba

et al. 2018

Environ. Sci. Technol.

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We explored the influence of a model organic ligand on mineral carbonation in nanoscale interfacial water films by conducting five time-resolved in situ X-ray diffraction (XRD) experiments at 50 °C. Forsterite was exposed to water-saturated supercritical carbon dioxide (90 bar) that had been equilibrated with 0-0.5 m citrate (CHO) solutions. The experimental results demonstrated that greater concentrations of citrate in the nanoscale interfacial water film promoted the precipitation of magnesite (MgCO) relative to nesquehonite (MgCO·3HO). At the highest concentrations tested, magnesite nucleation and growth were inhibited, lowering the carbonation rate constant from 9.1 × 10 to 3.6 × 10 s. These impacts of citrate were due to partial dehydration of Mg(aq) and the adsorption of citrate onto nuclei and magnesite surfaces. This type of information may be used to predict and tailor subsurface mineralization rates and pathways.

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“…While the dissociation of iron from hydroxamate siderophores is accelerated at high ionic strength, the association rate may be reduced. The exchange of iron from citrate to ferrioxamine B decreases at higher concentrations of NaCl [Ito et al, 2015]. Ito et al 2015 demonstrated that NaCl inhibits the adjunctive pathway by slowing the direct association of ferrioxamine B with the mono-citrate complex.…”

Section: Fe Exchange For Model Compounds Under Marine Conditionsmentioning

confidence: 99%

“…The exchange of iron from citrate to ferrioxamine B decreases at higher concentrations of NaCl [Ito et al, 2015]. Ito et al 2015 demonstrated that NaCl inhibits the adjunctive pathway by slowing the direct association of ferrioxamine B with the mono-citrate complex. Thus, salinity has a dual effect on decreasing the efficacy of hydroxamate siderophores as iron binding chelates.…”

Section: Fe Exchange For Model Compounds Under Marine Conditionsmentioning

confidence: 99%

Molecular determination of marine iron ligands by mass spectrometry

Boiteau¹

2016

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Abstract:Marine microbes produce a wide variety of metal binding organic ligands that regulate the solubility and availability of biologically important metals such as iron, copper, cobalt, and zinc.In marine environments where the availability of iron limits microbial growth and carbon fixation rates, the ability to access organically bound iron confers a competitive advantage. Thus, the compounds that microbes produced to acquire iron play an important role in biogeochemical carbon and metal cycling. However, the source, abundance, and identity of these compounds are poorly understood. To investigate these processes, sensitive methodologies were developed to gain a compound-specific window into marine iron speciation by combining trace metal clean sample collection and chromatography with inductively coupled plasma mass spectrometry (LC-ICPMS) and electrospray ionization mass spectrometry (LC-ESIMS). Coupled with isotope pattern assisted search algorithms, these tools provide a means to quantify and isolate specific iron binding ligands from seawater and marine cultures, identify them based on their mass and fragmentation spectra, and investigate their metal binding kinetics.Using these techniques, we investigated the distribution and diversity of marine iron binding ligands. In cultures, LC-ICPMS-ESIMS was used to identify new members of siderophore classes produced by marine cyanobacteria and heterotrophic bacteria, including synechobactins and marinobactins. Applications to natural seawater samples from the Pacific Ocean revealed a wide diversity of both known and novel metal compounds that are linked to specific nutrient regimes. Ferrioxamines B, E, and G were identified in productive coastal waters near California and Peru, in oligotrophic waters of the North and South Pacific Gyre, and in association with zooplankton grazers. Siderophore concentrations were up to five-fold higher in iron-deficient offshore waters (9pM) and were dominated by amphibactins, amphiphilic siderophores that partition into cell membranes. Furthermore, synechobactins were detected within nepheloid layers along the continental shelf. These siderophores reflect adaptations that impact dissolved iron bioavailability and thus have important consequences for marine ecosystem community structures and primary productivity. The ability to map and characterize these compounds has opened new opportunities to better understand mechanisms that link metals with the microbes that use them. 4Acknowledgements:

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Effect of ionic strength on ligand exchange kinetics between a mononuclear ferric citrate complex and siderophore desferrioxamine B

Cited by 10 publications

References 51 publications

Alteration of the Copper-Binding Capacity of Iron-Rich Humic Colloids during Transport from Peatland to Marine Waters

Alteration of the Copper-Binding Capacity of Iron-Rich Humic Colloids during Transport from Peatland to Marine Waters

Tunable Manipulation of Mineral Carbonation Kinetics in Nanoscale Water Films via Citrate Additives

Molecular determination of marine iron ligands by mass spectrometry

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