Electron paramagnetic resonance studies of a range of ferritins and haemosiderins

Nigel Deighton, Atieh Abu-Raqabah, Ian J. Rowland, Martyn C.R. Symons, Timothy J. Peters, Roberta J. Ward

Research output: Contribution to journalArticle

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Abstract

The major iron-storage proteins, ferritin and haemosiderin, comprise a protein skin which envelops closely packed Fe III largely in the form of iron oxyhydroxide. When fully loaded there can be ca. 4500 iron atoms in ferritin and in haemosiderin, but full loading is rare. The EPR spectra comprise very broad features stretching from near-zero field to well beyond the free-spin region. It is commonly supposed that the two proteins give rise to two quite different spectra, that for ferritin being dominated by a maximum in the derivative spectrum at g ≈ 6 (feature A) and that for haemosiderin by a maximum at g ≈ 2.2 (feature B). In attempts to obtain a clearer understanding of these spectral differences we have compared X- and Q-band spectra for a range of ferritins and haemosiderins, and find that the Q-band features are much better defined, with an optimal sensitivity at ca. 150 K. We find no clear distinction between ferritin and haemosiderin samples, some of which have a dominant A component and some a dominant B component. Electron microscopy has been used to estimate the loading of the proteins studied, and the results are discussed in terms of the dominance of either the A or B features.

Original languageEnglish (US)
Pages (from-to)3193-3197
Number of pages5
JournalJournal of the Chemical Society, Faraday Transactions
Volume87
Issue number19
DOIs
StatePublished - Dec 1 1991

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Hemosiderin
Ferritins
Paramagnetic resonance
electron paramagnetic resonance
proteins
iron
Proteins
Iron
electron microscopy
Electron microscopy
Stretching
Skin
sensitivity
Derivatives
estimates
Atoms
atoms

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

Deighton, Nigel ; Abu-Raqabah, Atieh ; Rowland, Ian J. ; Symons, Martyn C.R. ; Peters, Timothy J. ; Ward, Roberta J. / Electron paramagnetic resonance studies of a range of ferritins and haemosiderins. In: Journal of the Chemical Society, Faraday Transactions. 1991 ; Vol. 87, No. 19. pp. 3193-3197.
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Electron paramagnetic resonance studies of a range of ferritins and haemosiderins. / Deighton, Nigel; Abu-Raqabah, Atieh; Rowland, Ian J.; Symons, Martyn C.R.; Peters, Timothy J.; Ward, Roberta J.

In: Journal of the Chemical Society, Faraday Transactions, Vol. 87, No. 19, 01.12.1991, p. 3193-3197.

Research output: Contribution to journalArticle

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AB - The major iron-storage proteins, ferritin and haemosiderin, comprise a protein skin which envelops closely packed Fe III largely in the form of iron oxyhydroxide. When fully loaded there can be ca. 4500 iron atoms in ferritin and in haemosiderin, but full loading is rare. The EPR spectra comprise very broad features stretching from near-zero field to well beyond the free-spin region. It is commonly supposed that the two proteins give rise to two quite different spectra, that for ferritin being dominated by a maximum in the derivative spectrum at g ≈ 6 (feature A) and that for haemosiderin by a maximum at g ≈ 2.2 (feature B). In attempts to obtain a clearer understanding of these spectral differences we have compared X- and Q-band spectra for a range of ferritins and haemosiderins, and find that the Q-band features are much better defined, with an optimal sensitivity at ca. 150 K. We find no clear distinction between ferritin and haemosiderin samples, some of which have a dominant A component and some a dominant B component. Electron microscopy has been used to estimate the loading of the proteins studied, and the results are discussed in terms of the dominance of either the A or B features.

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