Kinetics of iron removal from monoferric and cobalt-labeled monoferric transferrins by diethylenetriaminepenta(methylenephosphonic acid) and diethylenetriaminepentaacetic acid

Harris, Wesley R.; Bali, Pawan K.; Crowley, Michael M.

doi:10.1021/ic00039a008

Cited by 27 publications

(33 citation statements)

References 7 publications

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“…The rates of iron release from transferrin show a first-order dependence on the ligand concentration for both NTA and DTPA [36,37]. Rates of iron release by NTA and DTPA were measured in the presence of increasing concentrations of the sulfonates SMS, MDS and EDS.…”

Section: Effect Of Sulfonates On Iron Removal By Nta and Dtpamentioning

confidence: 99%

“…We have proposed that the first-order term represents a separate reaction pathway for iron removal that involves the replacement of the synergistic carbonate by the incoming ligand and is not subject to a rate-limiting protein conformational change [32,[35][36][37][38]. The disulfonates show very distinct effects on the saturation and linear components of iron release.…”

Section: Anion Effects On Iron Releasementioning

confidence: 99%

“…Several ligands, particularly pyrophosphate [31][32][33][34][35] and phosphonic acids [23,[35][36][37][38], appear to follow saturation kinetics at low concentrations, but at higher ligand concentrations, the rate of iron release does not level off. Instead, it continues to increase linearly with the ligand concentration.…”

Section: Introductionmentioning

confidence: 99%

“…Perhaps the most intriguing variation in the pattern of liganddependence for iron removal from transferrin is shown by two simple aminocarboxylic acids, nitrilotriacetic acid (NTA) and diethylenetriaminepentaacetic acid (DTPA) [36,37]. Iron release by these ligands follows simple first order kinetics with respect to the ligand concentration.…”

Section: Introductionmentioning

confidence: 99%

“…A series of sulfonates with one or two anionic functional groups has been evaluated for its ability to alter the rates of iron removal by AHA, deferiprone (1,2-dimethyl-3-hydroxy-4-pyridinone), NTA, and DTPA. These ligands have been chosen because iron removal by AHA and deferiprone is reported to follow simple saturation kinetics [26,27], while iron removal by NTA and DTPA is reported to follow simple firstorder kinetics [36,37]. Sulfonic acids have been chosen because they are strictly non-chelating molecules that cannot remove any iron from transferrin, and thus introduce no complications in the analysis of the kinetic data.…”

Section: Introductionmentioning

confidence: 99%

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Allosteric effects of sulfonate anions on the rates of iron release from serum transferrin

Sharma

Harris

2011

Journal of Inorganic Biochemistry

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Section: Effect Of Sulfonates On Iron Removal By Nta and Dtpamentioning

confidence: 99%

Section: Anion Effects On Iron Releasementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Allosteric effects of sulfonate anions on the rates of iron release from serum transferrin

Sharma

Harris

2011

Journal of Inorganic Biochemistry

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Identification of possible kinetically significant anion‐binding sites in human serum transferrin using molecular modeling strategies

2003

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Certain anions have been shown experimentally to influence the rate of iron release from human serum transferrin (HST), implying the existence of one or more allosteric kinetically significant anion-binding (KISAB) sites on or near the surface of the protein. A rank-ordered selection of potential HST KISAB sites has been obtained using a novel three-stage molecular modeling strategy. The crystal structure of HST (1A8E.pdb) was first subjected to a heuristic analysis, in which positively charged and hydrogen-bonding residues on or near the surface of the protein were identified. In this stage, a preliminary electrostatic potential map was also calculated, yielding six preliminary sites. Next, energy-grid calculations were conducted in order to identify anion-protein interaction energy minima, which resulted in the inclusion of three additional sites. Finally, three anions already shown experimentally to demonstrate varied effects on HST iron-release kinetics were placed at each potential site; molecular dynamics and molecular mechanics calculations were performed in order to elucidate the hydrogen-bonding environment around each anion of the protein as well as to calculate anion-protein-binding energies.

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Aluminum ion removal from monoaluminum ovotransferrin by pyrophosphate

Yang

2004

Chin. J. Chem.

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The rates at which aluminurn was removed from the N-and C-terminal monoaluminum ovotransfemns by pyrophosphate were evaluated by UV difference spectra in 0.01 m o m Hepes, pH=7.4 and at 37 %. Pesudo first-order rate constants as a function of pyrophosphate concentration were measured. The results indicate that the pathways of aluminum removal are different. For the N-terminal binding site, aluminum removal follows simple saturation kinetics, while the removal of aluminum from the C-terminal binding site reverts to the combination of saturation and first-order kinetics. The saturation component is consistent with a rate-limiting conformational change in the protein as has been reported. We propose that the first-order kinetics mechanism is attributed to a pre-equilibrium process. The rate constants of saturation kinetics are accelerated from both terminals with the addition of 0.1 m o m chloride to the monoaluminum ovotransfemn solutions, whereas the rates of the first-order kinetics are decreased for the C-terminal binding site. The effect of chloride ionic strength causes a continuing increase on kobr for the N-and C-terminal binding sites. Moreover, the kinetics behavior of the N-terminal is more easily affected by chloride than that of the C-terminal. In the experiment presumably the N-terminal site is apparently kinetically more labile than the C-terminal site.

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Kinetics of iron removal from monoferric and cobalt-labeled monoferric transferrins by diethylenetriaminepenta(methylenephosphonic acid) and diethylenetriaminepentaacetic acid

Cited by 27 publications

References 7 publications

Allosteric effects of sulfonate anions on the rates of iron release from serum transferrin

Allosteric effects of sulfonate anions on the rates of iron release from serum transferrin

Identification of possible kinetically significant anion‐binding sites in human serum transferrin using molecular modeling strategies

Aluminum ion removal from monoaluminum ovotransferrin by pyrophosphate

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