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Iron (III) can be transferred between ferritin molecules.
E R Bauminger1, P M Harrison, D Hechel
1Racah Institute of Physics, Hebrew University of Jerusalem, Israel.
Proceedings. Biological Sciences
|June 22, 1991
Summary
Iron atoms can move between ferritin molecules during iron core formation. This surprising discovery, using Mössbauer spectroscopy, reveals iron migration to larger clusters, impacting models of ferritin iron storage.
Area of Science:
- Biochemistry
- Biophysics
- Materials Science
Background:
- Ferritin is a key iron-storage protein, sequestering up to 4500 iron atoms as ferrihydrite.
- Iron cores form gradually through Fe(II) oxidation within apoferritin.
Purpose of the Study:
- To investigate iron atom transfer between ferritin molecules during iron core biomineralization.
- To understand the dynamics of iron incorporation into the ferritin core.
Main Methods:
- Utilized Mössbauer spectroscopy with 57Fe and 56Fe isotopes to distinguish iron species.
- Performed experiments with horse spleen and recombinant human ferritin.
- Analyzed iron speciation in apoferritin before and after addition of iron-containing ferritin or NaCl solution.
Main Results:
- Identified 57Fe(III) in solitary and dinuclear sites in control apoferritin solutions.
- Observed that nearly all 57Fe(III) migrated to large clusters when pre-formed 56Fe(III)-ferritin was added.
- Demonstrated iron transfer from intermediate species to mature iron clusters within ferritin.
Conclusions:
- Iron atoms are mobile between ferritin molecules during the iron-core formation process.
- This inter-molecular iron migration challenges existing models of ferritin biomineralization.
- Models of ferritin iron-core formation must now incorporate this observed iron transfer mechanism.