Determination of conditional stability constants and kinetic constants for strong model Fe-binding ligands in seawater

Witter, Amy E.; Hutchins, David A.; Butler, Alison; Luther, George W.

doi:10.1016/s0304-4203(99)00087-0

Cited by 197 publications

(203 citation statements)

References 56 publications

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“…Enterobactin is a tris-catechol siderophore produced by terrestrial bacteria that forms photostabile Fe complexes (Raymond et al 2003). The conditional stability constants (K Fe9L cond ) of the siderophores fall within the range measured for natural ligands in seawater (10 9 -10 13 ; Witter et al 2000): DFB 5 10 11.8 , ferrichrome 5 10 12.9 (Witter et al 2000), aerobactin 5 10 12.5 (Harris et al 1979), and enterobactin 5 10 10.8 (Witter et al 2000).…”

Section: Methodsmentioning

confidence: 68%

Adaptive strategies by Southern Ocean phytoplankton to lessen iron limitation: Uptake of organically complexed iron and reduced cellular iron requirements

Strzepek

Maldonado

Hunter

et al. 2011

Limnology & Oceanography

153

245

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Section: Methodsmentioning

confidence: 68%

Adaptive strategies by Southern Ocean phytoplankton to lessen iron limitation: Uptake of organically complexed iron and reduced cellular iron requirements

Strzepek

Maldonado

Hunter

et al. 2011

Limnology & Oceanography

153

245

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“…A strong iron-binding ligand (termed L 1 with a log K Fe3+L1 ~23) is confined to the upper ocean where it is found at a mean concentration of ~0.44 nM. These log K Fe3+L1 values have been shown (Witter et al, 2000) to approximate to those of siderophores (log K Fe3+L = ~21-24) with which they share some structural similarities, notably the presence of hydroxymate Fe-binding functional groups (Mawji et al, 2008). Siderophores are believed to be produced by prokaryotic organisms to aid the acquisition of iron and, consistent with this, the L 1 ligand has been observed to be produced over several days in response to iron fertilisation experiments (Rue and Bruland, 1997).…”

Section: Si-2 Filterable Iron and Complexed Iron In Seawatermentioning

confidence: 95%

The Iron Biogeochemical Cycle Past and Present

Raiswell¹,

Canfield²

2012

GeochemPersp

568

445

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“…The ligands used in all the experiments were prepared using trace metal clean methods and were deferrated as needed; details of preparation protocols are presented in Hutchins et al (1999) and Witter et al (2000). The model ligands chosen for the Fe uptake experiments were desferrioxamine (a trihydroxamate siderophore), ferrichrome (a trihydroxamate siderophore), rhodotorulic acid (a dihydroxamate siderophore), protoporphyrin IX (a porphyrin compound), and an uncharacterized ligand from the cultured marine cyanobacterium Synechococcus sp.…”

Section: Methodsmentioning

confidence: 99%

Bioavailability of iron to Trichodesmium colonies in the western subtropical Atlantic Ocean

Achilles

Church

Wilhelm

et al. 2003

Limnology & Oceanography

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Trichodesmium provides new nitrogen (N) to marine surface waters via N 2 fixation, a process that requires a substantial amount of iron (Fe). Organic ligands in seawater that bind Fe could either increase or reduce the bioavailability of Fe. Electrochemical techniques indicate that these naturally occurring ligands have Fe-binding constants similar to those of siderophores and porphyrins, suggesting that these chelators play an important role in determining the bioavailability of Fe to cyanobacteria. We conducted Fe uptake experiments using model ligands labeled with 55 Fe to compare the bioavailability of inorganic Fe(III), porphyrin-bound Fe(III), and siderophorebound Fe(III) to field-collected Trichodesmium colonies. Inorganic Fe(III) and siderophore-bound Fe(III) were more bioavailable to Trichodesmium colonies than was porphyrin-bound Fe(III). Furthermore, the bioavailability of the siderophore-bound Fe(III) can be characterized by the functional groups of the siderophore. The dihydroxamate siderophore and an uncharacterized ligand from a cultured Synechococcus sp. increased the bioavailability of Fe compared to the trihydroxamate siderophores. Except for experiments with desferrioxamine B, dark incubations resulted in lower Fe uptake rates for all treatments, relative to parallel lighted incubations. This suggests that light enhances the photochemical dissociation of most of the ligand complexes or that light energy is required for the active transport of Fe complexed to the model ligands. The Fe uptake rate of Trichodesmium colonies also differed slightly on the basis of colony morphology, with higher uptake rates with ''puffs'' than ''tufts.'' These experiments show that Trichodesmium colonies are capable of discriminating between Fe bound to different organic complexes.

show abstract

Determination of conditional stability constants and kinetic constants for strong model Fe-binding ligands in seawater

Cited by 197 publications

References 56 publications

Adaptive strategies by Southern Ocean phytoplankton to lessen iron limitation: Uptake of organically complexed iron and reduced cellular iron requirements

Adaptive strategies by Southern Ocean phytoplankton to lessen iron limitation: Uptake of organically complexed iron and reduced cellular iron requirements

The Iron Biogeochemical Cycle Past and Present

Bioavailability of iron to Trichodesmium colonies in the western subtropical Atlantic Ocean

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