Stabilization of iron in a ferrous form by ferritin. A study using dispersive and conventional x-ray absorption spectroscopy.
Stabilization of iron in a bioavailable form is the function of ferritin, a protein of 24 subunits forming a coat around a core of less than or equal to 4500 hydrated iron atoms. The core of ferritin isolated from tissues contains Fe3+, but Fe2+ is required for experimental core formation in protein coats; reduction of Fe3+ to Fe2+ facilitates iron removal from protein coats. Using the differences in x-ray absorption spectra (x-ray absorption near edge structure) between Fe2+ and Fe3+ to monitor reconstitution of ferritin from Fe2+ and protein coats, we observed stabilization of Fe2+, apparently inside the coat. Mixtures of Fe2+ and Fe3+ persisted for greater than or equal to 16 h in air indicating that, in vivo, some iron in ferritin could be stored as Fe2+ and with Fe3+ could yield magnetite.
Rohrer
J S
JS
Department of Biochemistry, North Carolina State University, Raleigh 27695.
Joo
M S
MS
Dartyge
E
E
Sayers
D E
DE
Fontaine
A
A
Theil
E C
EC
D000818:Animals; D005293:Ferritins / Q000378:metabolism*; D006736:Horses; D007501:Iron / Q000378:metabolism*; D010618:Phenanthrolines / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D013057:Spectrum Analysis; D013154:Spleen / Q000378:metabolism; D014965:X-Rays
D010618:Phenanthrolines; D005293:Ferritins; D007501:Iron; C025205:1,10-phenanthroline